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D-Link DFL-1600 - Security Appliance User Manual - 3.2.5. Service Groups

Manual is about: NetDefendOS Network Security Firewall

Summary of DFL-1600 - Security Appliance

  • Page 1

    Network security solution http://www.Dlink.Com security security dfl-210/ 800/1600/ 2500 dfl-260/ 860/1660/ 2560(g) ver 2.26.01 network security firewall user manual.

  • Page 2: User Manual

    User manual dfl-210/260/800/860/1600/1660/2500/2560/2560g netdefendos version 2.26.01 d-link corporation no. 289, sinhu 3rd rd, neihu district, taipei city 114, taiwan r.O.C. Http://www.Dlink.Com published 2010-01-11.

  • Page 3

    User manual dfl-210/260/800/860/1600/1660/2500/2560/2560g netdefendos version 2.26.01 published 2010-01-11 copyright notice this publication, including all photographs, illustrations and software, is protected under international copyright laws, with all rights reserved. Neither this manual, nor any...

  • Page 4: Table Of Contents

    Table of contents preface ...............................................................................................................13 1. Netdefendos overview ....................................................................................15 1.1. Features ......................................

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    3.3. Interfaces ..............................................................................................86 3.3.1. Overview ...................................................................................86 3.3.2. Ethernet interfaces .............................................................

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    5.2. Dhcp servers ..................................................................................... 193 5.3. Static dhcp assignment ....................................................................... 196 5.3.1. Dhcp advanced settings .............................................................

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    7.4.4. Port translation ......................................................................... 313 7.4.5. Protocols handled by sat .......................................................... 313 7.4.6. Multiple sat rule matches ......................................................... 313 7.4.7. S...

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    10.1.3. Simple bandwidth limiting ....................................................... 405 10.1.4. Limiting bandwidth in both directions ........................................ 406 10.1.5. Creating differentiated limits with chains ................................... 407 10.1.6. Precedences .......

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    13.9. Miscellaneous settings ........................................................................ 474 a. Subscribing to security updates ........................................................................ 476 b. Idp signature groups .............................................................

  • Page 10: List Of Figures

    List of figures 1.1. Packet flow schematic part i ...........................................................................21 1.2. Packet flow schematic part ii ..........................................................................22 1.3. Packet flow schematic part iii ...........................

  • Page 11: List Of Examples

    List of examples 1. Example notation .............................................................................................13 2.1. Enabling remote management via https ...........................................................31 2.2. Enabling ssh remote access ..................................

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    4.13. If2 configuration - group translation ............................................................. 173 4.14. Setting up transparent mode for scenario 1 .................................................... 184 4.15. Setting up transparent mode for scenario 2 ......................................

  • Page 13: Preface

    Preface intended audience the target audience for this reference guide is administrators who are responsible for configuring and managing netdefend firewalls which are running the netdefendos operating system. This guide assumes that the reader has some basic knowledge of networks and network securi...

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    Items in the tree-view list at the left of the interface or in the menu bar or in a context menu need to be opened followed by information about the data items that need to be entered: 1. Go to item x > item y > item z 2. Now enter: • dataitem1: datavalue1 • dataitem2: datavalue2 highlighted content...

  • Page 15: 1.1. Features

    Chapter 1. Netdefendos overview this chapter outlines the key features of netdefendos. • features, page 15 • netdefendos architecture, page 18 • netdefendos state engine packet flow, page 21 1.1. Features d-link netdefendos is the base software engine that drives and controls the range of netdefend ...

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    Vpn netdefendos supports a range of virtual private network (vpn) solutions. Netdefendos supports ipsec, l2tp and pptp based vpns concurrently, can act as either server or client for all of the vpn types, and can provide individual security policies for each vpn tunnel. The details for this can be f...

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    Enables a device running netdefendos to distribute network load to multiple hosts. These features are discussed in detail in chapter 10, traffic management. Note threshold rules are only available on certain d-link netdefend product models. Operations and maintenance adminstrator management of netde...

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    1.2. Netdefendos architecture 1.2.1. State-based architecture the netdefendos architecture is centered around the concept of state-based connections. Traditional ip routers or switches commonly inspect all packets and then perform forwarding decisions based on information found in the packet headers...

  • Page 19: 1.2.3. Basic Packet Flow

    Netdefendos rule sets finally, rules which are defined by the administrator in the various rule sets are used for actually implementing netdefendos security policies. The most fundamental set of rules are the ip rules, which are used to define the layer 3 ip filtering policy as well as carrying out ...

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    • tcp/udp ports • icmp types • point in time in reference to a predefined schedule if a match cannot be found, the packet is dropped. If a rule is found that matches the new connection, the action parameter of the rule decides what netdefendos should do with the connection. If the action is drop, th...

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    1.3. Netdefendos state engine packet flow the diagrams in this section provide a summary of the flow of packets through the netdefendos state-engine. There are three diagrams, each flowing into the next. It is not necessary to understand these diagrams, however, they can be useful as a reference whe...

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    Figure 1.2. Packet flow schematic part ii the packet flow is continued on the following page. 1.3. Netdefendos state engine packet flow chapter 1. Netdefendos overview 22.

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    Figure 1.3. Packet flow schematic part iii 1.3. Netdefendos state engine packet flow chapter 1. Netdefendos overview 23.

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    Apply rules the figure below presents the detailed logic of the apply rules function in figure 1.2, “packet flow schematic part ii” above. Figure 1.4. Expanded apply rules logic 1.3. Netdefendos state engine packet flow chapter 1. Netdefendos overview 24.

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    1.3. Netdefendos state engine packet flow chapter 1. Netdefendos overview 25.

  • Page 26: 2.1. Managing Netdefendos

    Chapter 2. Management and maintenance this chapter describes the management, operations and maintenance related aspects of netdefendos. • managing netdefendos, page 26 • events and logging, page 53 • radius accounting, page 58 • hardware monitoring, page 63 • snmp monitoring, page 65 • the pcapdump ...

  • Page 27: 2.1.3. The Web Interface

    This feature is fully described in section 2.1.6, “secure copy”. Console boot menu before netdefendos starts running, a console connected directly to the netdefend firewall's rs232 port can be used to do basic configuration through the boot menu. This menu can be entered by pressing any console key ...

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    Netdefendos provides an intuitive web interface (webui) for management of the system via an ethernet interface using a standard web browser. This allows the administrator to perform remote management from anywhere on a private network or the public internet using a standard computer without having t...

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    Password is admin and admin. If the user credentials are correct, you will be transferred to the main web interface page. First time web interface logon and the setup wizard when logging on for the first time, the default username is always admin and the password is admin. After successful login, th...

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    For information about the default user name and password, see section 2.1.2, “the default administrator account”. Note: remote management access access to the web interface is regulated by the configured remote management policy. By default, the system will only allow web access from the internal ne...

  • Page 31: 2.1.4. The Cli

    Controlling access to the web interface by default, the web interface is accessible only from the internal network. If you need to enable access from other parts of the network, you can do so by modifying the remote management policy. Example 2.1. Enabling remote management via https command-line in...

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    Is described below), or remotely via an ethernet interface using the secure shell (ssh) protocol from an ssh client. The cli provides a comprehensive set of commands that allow the display and modification of configuration data as well as allowing runtime data to be displayed and allowing system mai...

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    Command appears it can be re-executed in it's original form or changed first before execution. Tab completion remembering all the commands and their options can be difficult. Netdefendos provides a feature called tab completion which means that pressing the tab key will cause automatically completio...

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    Not all object types belong in a category. The object type userauthrule is a type without a category and will appear in the category list after pressing tab at the beginning of a command. The category is sometimes also referred to as a context. Selecting object categories with some categories, it is...

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    Can be done either by referring to it by its index, that is to say its list position, or by alternatively using the name assigned to it. The cli reference guide lists the parameter options available for each netdefendos object, including the name= and index= options. Using unique names for convenien...

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    4. Press the enter key on the terminal. The netdefendos login prompt should appear on the terminal screen. Ssh (secure shell) cli access the ssh (secure shell) protocol can be used to access the cli over the network from a remote host. Ssh is a protocol primarily used for secure communication over i...

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    Else as soon as possible after initial startup. User passwords can be any combination of characters and cannot be greater than 256 characters in length. It is recommended to use only printable characters. To change the password to, for example, my-password the following cli commands are used. First ...

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    Automatically undone and the old configuration restored. Checking configuration integrity after changing a netdefendos configuration and before issuing the activate and commit commands, it is possible to explicitly check for any problems in a configuration using the command: gw-world:/> show -errors...

  • Page 39: 2.1.5. Cli Scripts

    • secure copy (scp) sessions. • web interface sessions connected by http or https. The command without any options gives a summary of currently open sessions: gw-world:/> sessionmanager session manager status ---------------------- active connections : 3 maximum allowed connections : 64 local idle s...

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    Gw-world:/> script -execute -name=my_script.Sgs script variables a script file can contain any number of script variables which are called: $1, $2, $3, $4......$n the values substituted for these variable names are specified as a list at the end of the script -execute command line. The number n in t...

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    Any output from script execution will appear at the cli console. Normally this output only consists of any error messages that occur during execution. To see the confirmation of each command completing, the -verbose option should be used: gw-world:/> script -execute -name=my_script2.Sgs -verbose sav...

  • Page 42: 2.1.6. Secure Copy

    This creates a script file called new_script_sgs which contains all the cli commands necessary to create all ip4address address objects in that unit's configuration. The created file's contents might, for example, be: add ip4address if1_ip address=10.6.60.10 add ip4address if1_net address=10.6.60.0/...

  • Page 43

    To upload and download files to or from the netdefend firewall, the secure copy (scp) protocol can be used. Scp is based on the ssh protocol and many freely available scp clients exist for almost all platforms. The command line examples below are based on the most common command format for scp clien...

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    Config.Bak full.Bak script/ sshclientkey/ apart from the individual files, the objects types listed are: • httpalgbanners/ - the banner files for user authentication html. Uploading these is described further in section 6.3.4.4, “customizing html pages”. • httpauthbanner/ - the banner files for html...

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    2.1.7. The console boot menu the netdefendos loader is the base software on top of which netdefendos runs and the administrator's direct interface to this is called the console boot menu (also known simply as the boot menu). This section discusses the boot menu options. Accessing the console boot me...

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    Selecting setting the password as soon as possible is recommended. After it is set, the console will prompt for the password before access is allowed to either the boot menu or the command line interface (cli). Initial options with a console password set if a console password is set then the initial...

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    Validation timeout specifies the amount of seconds to wait for the administrator to log in before reverting to the previous configuration. Default: 30 webui http port specifies the http port for the web interface. Default: 80 webui https port specifies the http(s) port for the web interface. Default...

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    Example 2.3. Listing configuration objects to find out what configuration objects exist, you can retrieve a listing of the objects. This example shows how to list all service objects. Command-line interface gw-world:/> show service a list of all services will be displayed, grouped by their respectiv...

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    Note when accessing object via the cli you can omit the category name and just use the type name. The cli command in the above example, for instance, could be simplified to: gw-world:/> show servicetcpudp telnet example 2.5. Editing a configuration object when you need to modify the behavior of netd...

  • Page 50

    Gw-world:/> show address ip4address myhost property value --------------------- ------------- name: myhost address: 192.168.10.10 userauthgroups: (none) nodefinedcredentials: no comments: (none) web interface 1. Go to objects > address book 2. Click on the add button 3. In the dropdown menu displaye...

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    Listing modified objects after modifying several configuration objects, you might want to see a list of the objects that were changed, added and removed since the last commit. Example 2.9. Listing modified configuration objects this example shows how to list configuration objects that have been modi...

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    The new configuration is now committed. Web interface 1. Go to configuration > save and activate in the menu bar 2. Click ok to confirm the web browser will automatically try to connect back to the web interface after 10 seconds. If the connection succeeds, this is interpreted by netdefendos that re...

  • Page 53: 2.2. Events And Logging

    2.2. Events and logging 2.2.1. Overview the ability to log and analyze system activities is an essential feature of netdefendos. Logging enables not only monitoring of system status and health, but also allows auditing of network usage and assists in trouble-shooting. Log message generation netdefen...

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    By default, netdefendos sends all messages of level info and above to configured log servers. The debug category is intended for troubleshooting only and should only be turned on if required when trying to solve a problem. All log messages of all severity levels are found listed in the netdefendos l...

  • Page 55

    In order to facilitate automated processing of all messages, netdefendos writes all log data to a single line of text. All data following the initial text is presented in the format name=value. This enables automatic filters to easily find the values they are looking for without assuming that a spec...

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    By d-link and defines the snmp objects and data types that are used to describe an snmp trap received from netdefendos. Note there is a different mib file for each model of netdefend firewall. Make sure that the correct file is used. For each netdefend firewall model there is one generic trap object...

  • Page 57

    Send limit this setting limits how many log packets netdefendos may send out per second. This value should never be set too low, as this may result in important events not being logged, nor should it be set too high. A situation where setting too high a value may cause damage is when netdefendos sen...

  • Page 58: 2.3. Radius Accounting

    2.3. Radius accounting 2.3.1. Overview within a network environment containing large numbers of users, it is advantageous to have one or a cluster of central servers that maintain user account information and are responsible for authentication and authorization tasks. The central database residing o...

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    Authentication server. • how authenticated - how the user was authenticated. This is set to either radius if the user was authenticated via radius, or local if the user was authenticated via a local user database. • delay time - the time delay (in seconds) since the accountingrequest packet was sent...

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    Tip: the meaning of the asterisk after a list entry the asterisk "*" symbol after an entry in the list above indicates that the sending of the parameter is optional and is configurable. 2.3.3. Interim accounting messages in addition to start and stop messages netdefendos can optionally periodically ...

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    Firewalls. This means that accounting information is automatically updated on both cluster members whenever a connection is closed. Two special accounting events are also used by the active unit to keep the passive unit synchronized: • an accountingstart event is sent to the inactive member in an ha...

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    Continue to be logged in. Disabling the setting will mean that the user will be logged out if the radius accounting server cannot be reached even though the user has been previously authenticated. Default: enabled logout at shutdown if there is an orderly shutdown of the netdefend firewall by the ad...

  • Page 63: 2.4. Hardware Monitoring

    2.4. Hardware monitoring availability certain d-link hardware models allow the administrator to use the cli to query the current value of various hardware operational parameters such as the current temperature inside the firewall. This feature is referred to as hardware monitoring. The d-link netdef...

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    The -verbose option displays the current values plus the configured ranges: gw-world:/> hwm -a -v 2 sensors available poll interval time = 500ms name [type][number] = low_limit] current_value [high_limit (unit) ----------------------------------------------------------------- sys temp [temp ][ 0] = ...

  • Page 65: 2.5. Snmp Monitoring

    2.5. Snmp monitoring overview simple network management protocol (snmp) is a standardized protocol for management of network devices. An snmp compliant client can connect to a network device which supports the snmp protocol to query and control it. Netdefendos supports snmp version 1 and version 2. ...

  • Page 66

    Snmp access. Port 161 is usually used for snmp and netdefendos always expects snmp traffic on that port. Remote access encryption it should be noted that snmp version 1 or 2c access means that the community string will be sent as plain text over a network. This is clearly insecure if a remote client...

  • Page 67

    Default: enabled snmp request limit maximum number of snmp requests that will be processed each second by netdefendos. Should snmp requests exceed this rate then the excess requests will be ignored by netdefendos. Default: 100 system contact the contact person for the managed node. Default: n/a syst...

  • Page 68: 2.6. The Pcapdump Command

    2.6. The pcapdump command a valuable diagnostic tool is the ability to examine the packets that enter and leave the interfaces of a netdefend firewall. For this purpose, netdefendos provides the cli command pcapdump which not only allows the examination of packet streams entering and leaving interfa...

  • Page 69

    It is possible to have multiple pcapdump executions being performed at the same time. The following points describe this feature: 1. All capture from all executions goes to the same memory buffer. The command can be launched multiple times with different interfaces specified. In this case the packet...

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    • the filename and extension can only contain the characters a-z, 0-9, "-" and "_". Combining filters it is possible to use several of these filter expressions together in order to further refine the packets that are of interest. For example we might want to examine the packets going to a particular...

  • Page 71: 2.7. Maintenance

    2.7. Maintenance 2.7.1. Auto-update mechanism a number of the netdefendos security features rely on external servers for automatic updates and content filtering. The intrusion prevention and detection system and anti-virus modules require access to updated signature databases in order to provide pro...

  • Page 72

    Be altered to include the date. For example, full.Bak might become full-20081121.Bak to show it is a snapshot of the state on november 21st, 2008. To restore a backup file, the administrator should upload the file to the netdefend firewall. The name of the file does not need to be changed in any way...

  • Page 73

    Important: any upgrades will be lost after a factory reset it should be understood that a reset to factory defaults is exactly that. Any netdefendos upgrades performed since the unit left the factory will be lost. Reset procedure for the netdefend dfl-210, 260, 800 and 860 to reset the netdefend dfl...

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    2.7.3. Restore to factory defaults chapter 2. Management and maintenance 74.

  • Page 75: Chapter 3. Fundamentals

    Chapter 3. Fundamentals this chapter describes the fundamental logical objects which make up a netdefendos configuration. These objects include such items as ip addresses and ip rules. Some exist by default and some must be defined by the administrator. In addition, the chapter explains the differen...

  • Page 76

    Corresponds to a 32 address net (netmask 255.255.255.224) and so on. The numbers 0-32 correspond to the number of binary ones in the netmask. For example: 192.168.0.0/24. Ip range a range of ip addresses is represented on the form a.B.C.D - e.F.G.H. Note that ranges are not limited to netmask bounda...

  • Page 77: 3.1.3. Ethernet Addresses

    Address=192.168.10.16-192.168.10.21 web interface 1. Go to objects > address book > add > ip address 2. Specify a suitable name for the ip range, for example wwwservers. 3. Enter 192.168.10.16-192.168.10.21 as the ip address 4. Click ok example 3.4. Deleting an address object to delete an object nam...

  • Page 78: 3.1.4. Address Groups

    Address=08-a3-67-bc-2e-f2 web interface 1. Go to objects > address book > add > ethernet address 2. Specify a suitable name for the ethernet address object, for example wwwsrv1_mac 3. Enter 08-a3-67-bc-2e-f2 as the mac address 4. Click ok 3.1.4. Address groups groups simplify configuration address o...

  • Page 79

    Client subsystem to store gateway address information acquired from a dhcp server. If a default gateway address has been provided during the setup phase, the wan_gw object will contain that address. Otherwise, the object will be left empty (in other words, the ip address will be 0.0.0.0/0). All-nets...

  • Page 80: 3.2. Services

    3.2. Services 3.2.1. Overview a service object is a reference to a specific ip protocol with associated parameters. A service definition is usually based on one of the major transport protocols such as tcp or udp, with the associated port number(s). The http service, for instance, is defined as usin...

  • Page 81

    Example 3.7. Viewing a specific service to view a specific service in the system: command-line interface gw-world:/> show service servicetcpudp echo the output will look similar to the following listing: property value ----------------- ---------------- name: echo destinationports: 7 type: tcpudp (t...

  • Page 82

    Uses port 25 and so on. For these types of service, the single port number is simply specified in the tcp/udp service object. Port ranges some services use a range of destination ports. As an example, the netbios protocol used by microsoft windows uses destination ports 137 to 139. To define a range...

  • Page 83: 3.2.3. Icmp Services

    Server is not in operation, an icmp error message is returned as the response. These icmp errors can either be ignored or allowed to pass through, back to the requesting application. Application layer gateways a tcp/udp service can be linked to an application layer gateway (alg) to enable deeper ins...

  • Page 84

    • code 2: protocol unreachable • code 3: port unreachable • code 4: cannot fragment • code 5: source route failed • redirect: the source is told that there is a better route for a particular packet. Codes assigned are as follows: • code 0: redirect datagrams for the network • code 1: redirect datagr...

  • Page 85: 3.2.5. Service Groups

    1. Go to objects > services > add > ip protocol service 2. Specify a suitable name for the service, for example vrrp 3. Enter 112 in the ip protocol control 4. Optionally enter virtual router redundancy protocol in the comments control 5. Click ok 3.2.5. Service groups a service group is, exactly as...

  • Page 86: 3.3. Interfaces

    3.3. Interfaces 3.3.1. Overview an interface is one of the most important logical building blocks in netdefendos. All network traffic that passes through or gets terminated in the system is done so through one or several interfaces. An interface can be seen as a doorway for network traffic to or fro...

  • Page 87: 3.3.2. Ethernet Interfaces

    Found in section 9.5, “pptp/l2tp”. • gre interfaces are used to establish gre tunnels. More information about this topic can be found in section 3.3.5, “gre tunnels”. Even though the various types of interfaces are very different in the way they are implemented and how they work, netdefendos treats ...

  • Page 88

    Data payload along with error checking bits. A pause between the broadcasting of individual frames allows devices time to process each frame before the next arrives and this pause becomes progressively smaller as the transmission rates get faster from normal ethernet to fast ethernet and then gigabi...

  • Page 89

    As explained next, this way of changing the ip address is not recommended. • instead, the ip_lan object in the netdefendos address book should be assigned the new address since it is this object that is used by many other netdefendos objects such as ip rules. The cli command to do this would be: gw-...

  • Page 90

    Web interface 1. Go to interfaces > ethernet 2. Select the ethernet interface of interest 3. Enable the enable dhcp client option 4. Click ok 3.3.2.1. Useful cli commands for ethernet interfaces this section summarizes the cli commands most commonly used for examining and manipulating netdefendos et...

  • Page 91

    Here, tab completion is used again at the end of the command line: gw-world:/> set address ip4address [] []: dnsserver1_ip interfaceaddresses/wan_br timesyncsrv1_ip interfaceaddresses/aux_ip interfaceaddresses/wan_dns1 interfaceaddresses/aux_net interfaceaddresses/wan_dns2 interfaceaddresses/dmz_ip ...

  • Page 92: 3.3.3. Vlan

    For a complete list of all cli options see the cli reference guide. 3.3.3. Vlan overview virtual lan (vlan) support in netdefendos allows the definition of one or more virtual lan interfaces which are associated with a particular physical interface. These are then considered to be logical interfaces...

  • Page 93

    With netdefendos vlans, the physical connections are as follows: • one of more vlans are configured on a physical netdefend firewall interface and this is connected directly to a switch. This link acts as a vlan trunk. The switch used must support port based vlans. This means that each port on the s...

  • Page 94

    The number of vlan interfaces that can be defined for a netdefendos installation is limited by the parameters of the license used. Different hardware models have different licenses and different limits on vlans. Summary of vlan setup it is important to understand that the administrator should treat ...

  • Page 95: 3.3.4. Pppoe

    Default: droplog 3.3.4. Pppoe 3.3.4.1. Overview point-to-point protocol over ethernet (pppoe) is a tunneling protocol used for connecting multiple users on an ethernet network to the internet through a common serial interface, such as a single dsl line, wireless device or cable modem. All the users ...

  • Page 96

    Ip address information pppoe uses automatic ip address allocation which is similar to dhcp. When netdefendos receives this ip address information from the isp, it stores it in a network object and uses it as the ip address of the interface. User authentication if user authentication is required by t...

  • Page 97: 3.3.5. Gre Tunnels

    2. Then enter: • name: pppoeclient • physical interface: wan • remote network: all-nets (as we will route all traffic into the tunnel) • service name: service name provided by the service provider • username: username provided by the service provider • password: password provided by the service prov...

  • Page 98

    Overhead. The lack of encryption can be acceptable in some circumstances if the tunneling is done across an internal network that is not public. Setting up gre like other tunnels in netdefendos such as an ipsec tunnel, a gre tunnel is treated as a logical interface by netdefendos, with the same filt...

  • Page 99

    The diagram above shows a typical gre scenario, where two netdefend firewalls a and b must communicate with each other through the intervening internal network 172.16.0.0/16. Any traffic passing between a and b is tunneled through the intervening network using a gre tunnel and since the network is i...

  • Page 100: 3.3.6. Interface Groups

    Setup for netdefend firewall "b" assuming that the network 192.168.11.0/24 is lannet on the lan interface, the steps for setting up netdefendos on b are as follows: 1. In the address book set up the following ip objects: • remote_net_a: 192.168.10.0/24 • remote_gw: 172.16.0.1 • ip_gre: 192.168.0.2 2...

  • Page 101

    • name: the name of the group to be used later • security/transport equivalent: if enabled, the interface group can be used as a destination interface in rules where connections might need to be moved between the interfaces - examples of such usage are route fail-over and ospf • interfaces: select t...

  • Page 102: 3.4. Arp

    3.4. Arp 3.4.1. Overview address resolution protocol (arp) is a protocol, which maps a network layer protocol address to a data link layer hardware address and it is used to resolve an ip address into its corresponding ethernet address. Arp operates at the osi data link layer (layer 2 - see appendix...

  • Page 103

    The default expiration time for dynamic arp entries is 900 seconds (15 minutes). This can be changed by modifying the advanced setting arp expire. The setting arp expire unknown specifies how long netdefendos will remember addresses that cannot be reached. This is done to ensure that netdefendos doe...

  • Page 104

    Hash size for vlan interfaces only. The default value is 64. 3.4.4. Static and published arp entries netdefendos supports defining static arp entries (static binding of ip addresses to ethernet addresses) as well as publishing ip addresses with a specific ethernet address. Static arp entries static ...

  • Page 105

    The corresponding netdefendos interface. Another use is publishing multiple addresses on an external interface, enabling netdefendos to statically address translate communications to these addresses and send it onwards to internal servers with private ip addresses. There are two publishing modes; pu...

  • Page 106

    Allowing this to take place may allow hijacking of local connections. However, not allowing this may cause problems if, for example, a network adapter is replaced, as netdefendos will not accept the new address until the previous arp cache entry has timed out. The advanced setting arp changes can be...

  • Page 107

    Default: droplog arp requests determines if netdefendos will automatically add the data in arp requests to its arp table. The arp specification states that this should be done, but as this procedure can facilitate hijacking of local connections, it is not normally allowed. Even if arprequests is set...

  • Page 108

    Broadcast addresses. Such claims are usually never correct. Default: droplog arp cache size how many arp entries there can be in the cache in total. Default: 4096 arp hash size hashing is used to rapidly look up entries in a table. For maximum efficiency, the hash size should be twice as large as th...

  • Page 109: 3.5. The Ip Rule Set

    3.5. The ip rule set 3.5.1. Security policies common policy characteristics netdefendos security policies designed by the administrator, regulate the way in which traffic can flow through the netdefend firewall. Policies in netdefendos are defined by different netdefendos rule sets. These rule sets ...

  • Page 110

    And are described in chapter 8, user authentication. Specifying any interface or network when specifying the filtering criteria in any of the rule sets specified above there are three useful predefined options that can be used: • for a source or destination network, the all-nets option is equivalent...

  • Page 111: 3.5.2. Ip Rule Evaluation

    If the ip rule used is an allow rule then this is bi-directional by default. The ordering of these steps is important. The route lookup occurs first to determine the exiting interface and then netdefendos looks for an ip rule that allows the traffic to leave on that interface. If a rule doesn't exis...

  • Page 112: 3.5.3. Ip Rule Actions

    Stateful inspection after initial rule evaluation of the opening connection, subsequent packets belonging to that connection will not need to be evaluated individually against the rule set. Instead, a highly efficient algorithm searches the state table for each packet to determine if it belongs to a...

  • Page 113

    Nat this functions like an allow rule, but with dynamic address translation (nat) enabled (see section 7.2, “nat” in chapter 7, address translation for a detailed description). Sat this tells netdefendos to perform static address translation. A sat rule always requires a matching allow, nat or fwdfa...

  • Page 114

    In order to help organise large numbers of entries in ip rule sets, it is possible to create ip rule set folders. These folders are just like a folder in a computer's file system. They are created with a given name and can then be used to contain all the ip rules that are related together as a group...

  • Page 115: 3.6. Schedules

    3.6. Schedules in some scenarios, it might be useful to control not only what functionality is enabled, but also when that functionality is being used. For instance, the it policy of an enterprise might stipulate that web traffic from a certain department is only allowed access outside that departme...

  • Page 116

    Return to the top level: gw-world:/main> cc configuration changes must be saved by then issuing an activate followed by a commit command. Web interface 1. Go to objects > schedules > add > schedule 2. Enter the following: • name: officehours 3. Select 08-17, monday to friday in the grid 4. Click ok ...

  • Page 117: 3.7. Certificates

    3.7. Certificates 3.7.1. Overview x.509 netdefendos supports digital certificates that comply with the itu-t x.509 standard. This involves the use of an x.509 certificate hierarchy with public-key cryptography to accomplish key distribution and entity authentication. References in this manual to a c...

  • Page 118

    Validity time a certificate is not valid forever. Each certificate contains the dates between which the certificate is valid. When this validity period expires, the certificate can no longer be used, and a new certificate has to be issued. Important make sure the netdefendos date and time are set co...

  • Page 119

    There are two types of certificates that can be uploaded: self-signed certificates and remote certificates belonging to a remote peer or ca server. Self-signed certificates can be generated by using one of a number of freely available utilities for doing this. Example 3.19. Uploading a certificate t...

  • Page 120

    • take out the relevant parts of the .Pem file to form the required .Cer and .Key files. The detailed steps for the above stages are as follows: 1. Create the gateway certificate on the windows ca server and export it to a .Pfx file on the local netdefendos management workstation disk. 2. Now conver...

  • Page 121: 3.8. Date And Time

    3.8. Date and time 3.8.1. Overview correctly setting the date and time is important for netdefendos to operate properly. Time scheduled policies, auto-update of the idp and anti-virus databases, and other product features require that the system clock is accurately set. In addition, log messages are...

  • Page 122: 3.8.3. Time Servers

    Counted as being inside a given time zone will then have the same local time and this will be one of the integer offsets from gmt. The netdefendos time zone setting reflects the time zone where the netdefend firewall is physically located. Example 3.22. Setting the time zone to modify the netdefendo...

  • Page 123

    Netdefendos is able to adjust the clock automatically based on information received from one or more time servers which provide a highly accurate time, usually using atomic clocks. Using time servers is highly recommended as it ensures netdefendos will have its date and time aligned with other netwo...

  • Page 124

    • secondary time server: dns:ntp2.Sp.Se 4. Click ok the time server urls must have the prefix dns: to specify that they should be resolved with a dns server. Netdefendos must therefore also have a dns server defined so this resolution can be performed. Note if the timesyncinterval parameter is not s...

  • Page 125

    Adjust value. It is then possible to manually force a synchronization and disregard the maximum adjustment parameter. Example 3.27. Forcing time synchronization this example demonstrates how to force time synchronization, overiding the maximum adjustment setting. Command-line interface gw-world:/> t...

  • Page 126

    Default: 0 dst offset daylight saving time offset in minutes. Default: 0 dst start date what month and day dst starts, in the format mm-dd. Default: none dst end date what month and day dst ends, in the format mm-dd. Default: none time sync server type type of server for time synchronization, udptim...

  • Page 127

    Default: 600 group interval interval according to which server responses will be grouped. Default: 10 3.8.4. Settings summary for date and time chapter 3. Fundamentals 127.

  • Page 128: 3.9. Dns

    3.9. Dns overview a dns server can resolve a fully qualified domain name (fqdn) into the corresponding numeric ip address. Fqdns are unambiguous textual domain names which specify a node's unique position in the internet's dns tree hierarchy. Fqdn resolution allows the actual physical ip address to ...

  • Page 129

    Dynamic dns a dns feature offered by netdefendos is the ability to explicitly inform dns servers when the external ip address of the netdefend firewall has changed. This is sometimes referred to as dynamic dns and is useful where the netdefend firewall has an external ip address that can change. Dyn...

  • Page 130

    3.9. Dns chapter 3. Fundamentals 130

  • Page 131: Chapter 4. Routing

    Chapter 4. Routing this chapter describes how to configure ip routing in netdefendos. • overview, page 131 • static routing, page 132 • policy-based routing, page 146 • route load balancing, page 151 • dynamic routing, page 157 • multicast routing, page 165 • transparent mode, page 177 4.1. Overview...

  • Page 132: 4.2. Static Routing

    4.2. Static routing the most basic form of routing is known as static routing. The word "static" refers to the fact that entries in the routing table are manually added and are therefore permanent (or static) by nature. Due to this manual approach, static routing is most appropriate to use in smalle...

  • Page 133

    This parameter usually doesn't need to be specified. If it is specified, netdefendos responds to arp queries sent to this address. A special section below explains this parameter in more depth. Local ip address and gateway are mutually exclusive and either one or the other should be specified. • met...

  • Page 134

    Route # interface destination gateway 4 wan all-nets 195.66.77.4 the above routing table provides the following information: • route #1 all packets going to hosts on the 192.168.0.0/24 network should be sent out on the lan interface. As no gateway is specified for the route entry, the host is assume...

  • Page 135

    • interface: the interface on which the second network is found. • network: the ip address range of the second network. • local ip address: an address within the second network's ip range. When the default gateway of the second network's clients is now set to the same value as the local ip address o...

  • Page 136: 4.2.2. Static Routing

    Something that is not intuitive when trying to understand routing in netdefendos is the fact that all traffic must have two routes associated with it. Not only must a route be defined for the destination network of a connection but also for the source network. The route that defines the source netwo...

  • Page 137

    Active routes: network destination netmask gateway interface metric 0.0.0.0 0.0.0.0 192.168.0.1 192.168.0.10 20 10.0.0.0 255.0.0.0 10.4.2.143 10.4.2.143 1 10.4.2.143 255.255.255.255 127.0.0.1 127.0.0.1 50 10.255.255.255 255.255.255.255 10.4.2.143 10.4.2.143 50 85.11.194.33 255.255.255.255 192.168.0....

  • Page 138

    Gw-world:/> cc routingtable main gw-world:/main> show route # interface network gateway local ip - --------- -------- ------------- -------- 1 wan all-nets 213.124.165.1 (none) 2 lan lannet (none) (none) 3 wan wannet (none) (none) to see the active routing table enter: gw-world:/> routes flags netwo...

  • Page 139

    Your isp for public internet access. If using the netdefendos setup wizard, this route is also added automatically. However, the option also exists for any physical interface to indicate that it should be used for connection to the internet. In the web interface this is an advanced setting in the et...

  • Page 140: 4.2.3. Route Failover

    3. The main window will list the active routing table, including the core routes tip: understanding output from the routes command for detailed information about the output of the cli routes command. Please see the cli reference guide. 4.2.3. Route failover overview netdefend firewalls are often dep...

  • Page 141

    Interface link status netdefendos will monitor the link status of the interface specified in the route. As long as the interface is up, the route is diagnosed as healthy. This method is appropriate for monitoring that the interface is physically attached and that the cabling is working as expected. ...

  • Page 142

    Even if a route has been disabled, netdefendos will continue to check the status of that route. Should the route become available again, it will be re-enabled and existing connections will automatically be transferred back to it. Route interface grouping when using route monitoring, it is important ...

  • Page 143

    Provides the additional capability to perform host monitoring. This feature means that one or more external host systems can be routinely polled to check that a particular route is available. The advantages of host monitoring are twofold: • in a complex network topology it is more reliable to check ...

  • Page 144

    Minimum value allowed is 100 ms. • sample the number of polling attempts used as a sample size for calculating the percentage loss and the average latency. This value cannot be less than 1. • maximum failed poll attempts the maximum permissible number of polling attempts that fail. If this number is...

  • Page 145: 4.2.5. Proxy Arp

    4.2.5. Proxy arp overview as discussed previously in section 3.4, “arp”, the arp protocol facilitates a mapping between an ip address and the mac address of a node on an ethernet network. However, situations may exist where a network running ethernet is separated into two parts with a routing device...

  • Page 146: 4.3. Policy-Based Routing

    4.3. Policy-based routing 4.3.1. Overview policy-based routing (pbr) is an extension to the standard routing described previously. It offers administrators significant flexibility in implementing routing decision policies by being able to define rules so alternative routing tables are used. Normal r...

  • Page 147

    When looking up policy-based rules, it is the first matching rule found that is triggered. 4.3.4. Routing table selection when a packet corresponding to a new connection first arrives, the processing steps are as follows to determine which routing table is chosen: 1. The routing rules must first be ...

  • Page 148

    Important: ensure all-nets appears in the main table a common mistake with policy-based routing is the absence of the default route with a destination interface of all-nets in the default main routing table. If there is no route that is an exact match then the absence of a default all-nets route wil...

  • Page 149

    Example 4.5. Policy-based routing configuration this example illustrates a multiple isp scenario which is a common use of policy-based routing. The following is assumed: • each isp will give you an ip network from its network range. We will assume a 2-isp scenario, with the network 10.10.10.0/24 bel...

  • Page 150

    Note rules in the above example are added for both inbound and outbound connections. 4.3.5. The ordering parameter chapter 4. Routing 150

  • Page 151: 4.4. Route Load Balancing

    4.4. Route load balancing overview netdefendos provides the option to perform route load balancing (rlb). This is the ability to distribute traffic over multiple alternate routes based on a number of predefined distribution algorithms. The purpose of this feature is to provide the following: • balan...

  • Page 152

    3. If more than one matching route is found then rlb is used to choose which one to use. This is done according to which algorithm is selected in the table's rlb instance object: • round robin successive routes are chosen from the matching routes in a "round robin" fashion provided that the metric o...

  • Page 153

    Spillover limits are set separately for ingoing and outgoing traffic with only one of these typically being specified. If both are specified then only one of them needs to be exceeded continuously for hold timer seconds for the next matching route to be chosen. The units of the limits, such as mbps,...

  • Page 154

    Several alternative routes can be set up, each with their own interface limits and each with a different metric. The route with the lowest metric is chosen first and when that route's interface limits are exceeded, the route with the next highest metric is then chosen. When that new route's interfac...

  • Page 155

    To the firewall interfaces wan1 and wan2. Rlb will be used to balance the connections between the two isps. Figure 4.6. A route load balancing scenario we first need to define two routes to these two isps in the main routing table as shown below: route no. Interface destination gateway metric 1 wan1...

  • Page 156

    Achieve stickiness so the server always sees the same source ip address (wan1 or wan2) from a single client. Command-line interface gw-world:/> add routebalancinginstance main algorithm=destination web interface 1. Go to routing > route load balancing > instances > add > route balancing instance 2. ...

  • Page 157: 4.5. Dynamic Routing

    4.5. Dynamic routing 4.5.1. Dynamic routing overview dynamic routing is different to static routing in that the netdefend firewall will adapt to changes of network topology or traffic load automatically. Netdefendos first learns of all the directly connected networks and gets further route informati...

  • Page 158: 4.5.2. Ospf

    Comparing dynamic routing algorithms due to the fact that the global link state information is maintained everywhere in a network, ls algorithms offer a high degree of configuration control and scalability. Changes result in broadcasts of just the updated information to other routers which means fas...

  • Page 159

    Link-state database, describing the as topology. From the information in this database, each router constructs a tree of shortest paths with itself as root. This shortest-path tree gives the best route to each destination in the as. All ospf protocol exchanges can be authenticated. This means that o...

  • Page 160

    Become neighbors as soon as they see themselves listed in the neighbor's hello packet. This way, a two way communication is guaranteed. The following neighbor states are defined: down this is the initial state of the neighbor relationship. Init when a hello packet is received from a neighbor, but do...

  • Page 161

    In the above example, the virtual link is configured between fw1 and fw2 on area 1, as it is used as the transit area. In this configuration only the router id has to be configured. The diagram shows that fw2 needs to have a virtual link to fw1 with router id 192.168.1.1 and vice versa. These virtua...

  • Page 162

    The virtual link is configured between fw1 and fw2 on area 1, as it is used as the transit area. In the configuration only the router id have to be configured, as in the example above show fw2 need to have a virtual link to fw1 with the router id 192.168.1.1 and vice versa. These vlinks need to be c...

  • Page 163

    Example 4.7. Importing routes from an ospf as into the main routing table in this example, the routes received using ospf will be added into the main routing table. First of all a dynamic routing policy filter needs to be created. The filter needs to have a name, in this example importospfroutes is ...

  • Page 164

    Destinationinterface=wan destinationnetworkexactly=all-nets web interface 1. Go to routing > dynamic routing rules > add > dynamic routing policy rule 2. Specify a suitable name for the filter, for example exportdefroute 3. For from routing table select main routing table 4. Choose wan for destinati...

  • Page 165: 4.6. Multicast Routing

    4.6. Multicast routing 4.6.1. Overview certain types of internet interactions, such as conferencing and video broadcasts, require a single client or host to send the same packet to multiple receivers. This could be achieved through the sender duplicating the packet with different receiving ip addres...

  • Page 166

    The multiplex rule can operate in one of two modes: using igmp the traffic flow specified by the multiplex rule must have been requested by hosts using igmp before any multicast packets are forwarded through the specified interfaces. This is the default behavior of netdefendos. Not using igmp the tr...

  • Page 167

    Note: sat multiplex rules must have a matching allow rule remember to add an allow rule that matches the sat multiplex rule. The matching rule could also be a nat rule for source address translation (see below) but cannot be a fwdfast or sat rule. Example 4.9. Forwarding of multicast traffic using t...

  • Page 168

    Gw-world:/> cc ipruleset main the cli command to create the multiplex rule is then: add iprule sourcenetwork= sourceinterface= destinationinterface= destinationnetwork= action=multiplexsat service= multiplexargument={outif1;ip1},{outif2;ip2},{outif3;ip3}... The two values {outif;ip} represent a comb...

  • Page 169: 4.6.3. Igmp Configuration

    Tip as previously noted, remember to add an allow rule matching the sat multiplex rule. Example 4.10. Multicast forwarding - address translation the following sat multiplex rule needs to be configured to match the scenario described above: web interface a. Create a custom service for multicast calle...

  • Page 170

    To new multicast groups or change current multicast subscriptions. Igmp queries queries are igmp messages sent from the router towards the hosts in order to make sure that it will not close any stream that some host still wants to receive. Normally, both these types of rules has to be specified for ...

  • Page 171

    In snoop mode, the router will act transparently between the hosts and another igmp router. It will not send any igmp queries. It will only forward queries and reports between the other router and the hosts. In proxy mode, the router will act as an igmp router towards the clients and actively send q...

  • Page 172

    • source interface: wan • source network: upstreamrouterip • destination interface: core • destination network: auto • multicast source: 192.168.10.1 • multicast group: 239.192.10.0/24 4. Click ok 4.6.3.2. Igmp rules configuration - address translation the following examples illustrates the igmp rul...

  • Page 173

    2. Under general enter: • name: a suitable name for the rule, for example queries_if1 • type: query • action: proxy • output: if1 (this is the relay interface) 3. Under address filter enter: • source interface: wan • source network: upstreamrouterip • destination interface: core • destination networ...

  • Page 174

    • name: a suitable name for the rule, for example queries_if2 • type: query • action: proxy • output: if2 (this is the relay interface) 3. Under address filter enter: • source interface: wan • source network: upstreamrouterip • destination interface: core • destination network: auto • multicast sour...

  • Page 175

    Igmp router version the igmp protocol version that will be globally used on interfaces without a configured igmp setting. Multiple querying igmp routers on the same network must use the same igmp version. Global setting on interfaces without an overriding igmp setting. Default: igmpv3 igmp last memb...

  • Page 176

    Default: 2 igmp startup query interval the interval of general queries in milliseconds used during the startup phase. Global setting on interfaces without an overriding igmp setting. Default: 30,000 igmp unsolicated report interval the time in milliseconds between repetitions of an initial membershi...

  • Page 177: 4.7. Transparent Mode

    4.7. Transparent mode 4.7.1. Overview transparent mode usage the netdefendos transparent mode feature allows a netdefend firewall to be placed at a point in a network without any reconfiguration of the network and without hosts being aware of its presence. All netdefendos features can then be used t...

  • Page 178

    The osi model. If the firewall is placed into a network for the first time, or if network topology changes, the routing configuration must therefore be checked and adjusted to ensure that the routing table is consistent with the new layout. Reconfiguration of ip settings may be required for pre-exis...

  • Page 179

    The network. Discovery is done by netdefendos sending out arp as well as icmp (ping) requests, acting as the initiating sender of the original ip packet for the destination on the interfaces specified in the switch route. If an arp reply is received, netdefendos will update the cam table and layer 3...

  • Page 180

    Routing table will be connected together by netdefendos and no matter how interfaces are associated with the switch routes, transparency will exist between them. For example, if the interfaces if1 to if6 appear in a switch routes in routing table a, the resulting interconnections will be as illustra...

  • Page 181

    Mode. Two vlan interfaces with the same vlan id are defined on the two physical interfaces and they are called vlan5_if1 and vlan5_if2. For the vlan to operate in transparent mode we create a routing table with the ordering set to only and which contains the following 2 switch routes: network interf...

  • Page 182

    The non-switch route usually needed to allow internet access would be: route type interface destination gateway non-switch if1 all-nets gw-ip now lets suppose the netdefend firewall is to operate in transparent mode between the users and the isp. The illustration below shows how, using switch routes...

  • Page 183

    Route type interface destination gateway switch if1 all-nets switch if2 all-nets non-switch if1 85.12.184.39 gw-ip non-switch if1 194.142.215.15 gw-ip the appropriate ip rules will also need to be added to the ip rule set to allow internet access through the netdefend firewall. Grouping ip addresses...

  • Page 184

    Example 4.14. Setting up transparent mode for scenario 1 web interface configure the interfaces: 1. Go to interfaces > ethernet > edit (wan) 2. Now enter: • ip address: 10.0.0.1 • network: 10.0.0.0/24 • default gateway: 10.0.0.1 • transparent mode: enable 3. Click ok 4. Go to interfaces > ethernet >...

  • Page 185

    • destination network: all-nets (0.0.0.0/0) 3. Click ok scenario 2 here the netdefend firewall in transparent mode separates server resources from an internal network by connecting them to a separate interface without the need for different address ranges. All hosts connected to lan and dmz (the lan...

  • Page 186

    • network: 10.0.0.0/24 • transparent mode: disable • add route for interface network: disable 3. Click ok 4. Go to interfaces > ethernet > edit (dmz) 5. Now enter: • ip address: 10.0.0.2 • network: 10.0.0.0/24 • transparent mode: disable • add route for interface network: disable 6. Click ok configu...

  • Page 187

    • name: http-wan-to-dmz • action: sat • service: http • source interface: wan • destination interface: dmz • source network: all-nets • destination network: wan_ip • translate: select destination ip • new ip address: 10.1.4.10 6. Click ok 7. Go to rules > ip rules > add > iprule 8. Now enter: • name...

  • Page 188

    • multiple spanning tree protocol (mstp) • cisco proprietary pvst+ protocol (per vlan spanning tree plus) netdefendos checks the contents of bdpu messages to make sure the content type is supported. If it is not, the frame is dropped. Enabling/disabling bpdu relaying bpdu relaying is disabled by def...

  • Page 189

    Default: dynamic transparency ats expire defines the lifetime of an unanswered arp transaction state (ats) entry in seconds. Valid values are 1-60 seconds. Default: 3 seconds transparency ats size defines the maximum total number of arp transaction state (ats) entries. Valid values are 128-65536 ent...

  • Page 190

    • accept - accept packet • acceptlog - accept packet and log • rewrite - rewrite to the mac of the forwarding interface • rewritelog - rewrite to the mac of the forwarding interface and log • drop - drop packets • droplog - drop and log packets default: droplog relay spanning-tree bpdus when set to ...

  • Page 191

    4.7.5. Advanced settings for transparent mode chapter 4. Routing 191.

  • Page 192: Chapter 5. Dhcp Services

    Chapter 5. Dhcp services this chapter describes dhcp services in netdefendos. • overview, page 192 • dhcp servers, page 193 • static dhcp assignment, page 196 • dhcp relaying, page 198 • ip pools, page 201 5.1. Overview dynamic host configuration protocol (dhcp) is a protocol that allows network adm...

  • Page 193: 5.2. Dhcp Servers

    5.2. Dhcp servers dhcp servers assign and manage the ip addresses taken from a specified address pool. In netdefendos, dhcp servers are not limited to serving a single range of ip addresses but can use any ip address range that can be specified by a netdefendos ip address object. Multiple dhcp serve...

  • Page 194

    • wins servers - wins servers the client can use for wins lookup. • next server - the ip address of the next server in the boot process, this is usually a tftp server. In addition, custom options can be specified in order to have the dhcp servers hand out all options supported by the dhcp standard. ...

  • Page 195

    10.4.13.241 00-0c-29-04-f8-3c active(static) 10.4.13.242 00-1e-0b-aa-ae-11 active(static) 10.4.13.243 00-1c-c4-36-6c-c4 inactive(static) 10.4.13.244 00-00-00-00-02-14 inactive(static) 10.4.13.254 00-00-00-00-02-54 inactive(static) 10.4.13.1 00-12-79-3b-dd-45 active 10.4.13.2 00-12-79-c4-06-e7 active...

  • Page 196

    5.3. Static dhcp assignment where the administrator requires a fixed relationship between a client and the assigned ip address, netdefendos allows the assignment of a given ip to a specific mac address. Example 5.3. Setting up static dhcp this example shows how to assign the ip address 192.168.1.1 t...

  • Page 197

    Auto save policy what policy should be used to save the lease database to the disk, possible settings are disabled, reconfshut or reconfshuttimer. Default: reconfshut lease store interval how often, in seconds, the leases database should be saved to disk if dhcpserver_saveleasepolicy is set to recon...

  • Page 198: 5.4. Dhcp Relaying

    5.4. Dhcp relaying the dhcp problem with dhcp, clients send requests to locate the dhcp server(s) using broadcast messages. However, broadcasts are normally only propagated across the local network. This means that the dhcp server and client always need to be on the same physical network. In a large...

  • Page 199

    • name: ipgrp-dhcp • interfaces: select vlan1 and vlan2 from the available list and put them into the selected list. 3. Click ok adding a dhcp relayer called as vlan-to-dhcpserver: 1. Go to system > dhcp > add > dhcp relay 2. Now enter: • name: vlan-to-dhcpserver • action: relay • source interface: ...

  • Page 200

    Will be reduced down to this value. Default: 10000 seconds max auto routes how many relays that can be active at the same time. Default: 256 auto save policy what policy should be used to save the relay list to the disk, possible settings are disabled, reconfshut, or reconfshuttimer. Default: reconf...

  • Page 201: 5.5. Ip Pools

    5.5. Ip pools overview ip pools are used to offer other subsystems access to a cache of dhcp ip addresses. These addresses are gathered into a pool by internally maintaining a series of dhcp clients (one per ip). The dhcp servers used by a pool can either be external or be dhcp servers defined in ne...

  • Page 202

    Server keeps giving out the same ip for each client. Prefetched leases specifies the number of leases to keep prefetched. Prefetching will improve performance since there will not be any wait time when a system requests an ip (while there exists prefetched ips). Maximum free the maximum number of "f...

  • Page 203

    5.5. Ip pools chapter 5. Dhcp services 203.

  • Page 204: 6.1. Access Rules

    Chapter 6. Security mechanisms this chapter describes netdefendos security features. • access rules, page 204 • algs, page 207 • web content filtering, page 255 • anti-virus scanning, page 272 • intrusion detection and prevention, page 278 • denial-of-service attack prevention, page 289 • blacklisti...

  • Page 205

    Vpns provide one means of avoiding spoofing but where a vpn is not an appropriate solution then access rules can provide an anti-spoofing capability by providing an extra filter for source address verification. An access rule can verify that packets arriving at a given interface do not have a source...

  • Page 206

    Problems in case a rule is preventing some other function, such as vpn tunnel establishment, from working properly. Example 6.1. Setting up an access rule a rule is to be defined that ensures no traffic with a source address not within the lannet network is received on the lan interface. Command-lin...

  • Page 207: 6.2. Algs

    6.2. Algs 6.2.1. Overview to complement low-level packet filtering, which only inspects packet headers in protocols such as ip, tcp, udp, and icmp, netdefend firewalls provide application layer gateways (algs) which provide filtering at the higher application osi level. An alg object acts as a media...

  • Page 208: 6.2.2. The Http Alg

    Maximum connection sessions the service associated with an alg has a configurable parameter associated with it called max sessions and the default value varies according to the type of alg. For instance, the default value for the http alg is 1000. This means that a 1000 connections are allowed in to...

  • Page 209

    Anti-virus scanning, if it is enabled, is always applied to the http traffic even if it is whitelisted. These features are described in depth in section 6.3.3, “static content filtering”. • dynamic content filtering - access to specific urls can be allowed or blocked according to policies for certai...

  • Page 210

    Note: similarities with other netdefendos features the verify mime type and allow/block selected types options work in the same way for the ftp, pop3 and smtp algs. • download file size limit - a file size limit can additionally be specified for any single download (this option is available only for...

  • Page 211: 6.2.3. The Ftp Alg

    For example, the entry *.Some_domain.Com will block all pages whose urls end with some_domain.Com. If we want to now explicitly allow one particular page then this can be done with an entry in the whitelist of the form my_page.My_company.Com and the blacklist will not prevent this page from being re...

  • Page 212

    Allow traffic from all ports on the ftp server to all ports on the ftp client. Obviously, this is not a good solution. When passive mode is used, the firewall does not need to allow connections from the ftp server. On the other hand, netdefendos still does not know what port the ftp client tries to ...

  • Page 213

    Scanning”. Ftp alg with zonedefense used together with the ftp alg, zonedefense can be configured to protect an internal network from virus spreading servers and hosts. This is relevant to 2 scenarios: • a. Infected clients that need to be blocked. • b. Infected servers that need to be blocked. A. B...

  • Page 214

    To make it possible to connect to this server from the internet using the ftp alg, the ftp alg and rules should be configured as follows: web interface a. Define the alg: 1. Go to objects > alg > add > ftp alg 2. Enter name: ftp-inbound 3. Check allow client to use active mode 4. Uncheck allow serve...

  • Page 215

    • name: sat-ftp-inbound • action: sat • service: ftp-inbound 3. For address filter enter: • source interface: any • destination interface: core • source network: all-nets • destination network: wan_ip (assuming the external interface has been defined as this) 4. For sat check translate the destinati...

  • Page 216

    Example 6.3. Protecting ftp clients in this scenario shown below the netdefend firewall is protecting a workstation that will connect to ftp servers on the internet. To make it possible to connect to these servers from the internal network using the ftp alg, the ftp alg and rules should be configure...

  • Page 217: 6.2.4. The Tftp Alg

    Rules (using public ips). The following rule needs to be added to the ip rules if using public ip's; make sure there are no rules disallowing or allowing the same kind of ports/traffic before these rules. The service in use is the ftp-outbound, which should be using the alg definition ftp-outbound a...

  • Page 218: 6.2.5. The Smtp Alg

    Allow/disallow read the tftp get function can be disabled so that files cannot be retrieved by a tftp client. The default value is allow. Allow/disallow write the tftp put function can be disabled so that files cannot be written by a tftp client. The default value is allow. Remove request option spe...

  • Page 219

    This is a very useful feature to have since it is possible to put in a block against either an infected client or an infected server sending large amounts of malware generated emails. Email size limiting a maximum allowable size of email messages can be specified. This feature counts the total amoun...

  • Page 220

    4. Anti-virus scanning (if enabled). As described above, if an address is found on the whitelist then it will not be blocked if it also found on the blacklist. Spam filtering, if it is enabled, is still applied to whitelisted addresses but emails flagged as spam will not be tagged nor dropped, only ...

  • Page 221

    The netdefendos smtp alg does not support all esmtp extensions including pipelining and chunking. The alg therefore removes any unsupported extensions from the supported extension list that is returned to the client by an smtp server behind the netdefend firewall. When an extension is removed, a log...

  • Page 222

    Security issue on the public internet. Unsolicited email, sent out in massive quantities by groups known as spammers, can waste resources, transport malware as well as try to direct the reader to webpages which might exploit browser vulnerabilities. Integral to the netdefendos smtp alg is a spam mod...

  • Page 223

    Weighted sum can then be calculated based on all responses. The administrator can configure one of the following actions based on the sum calculated: 1. Dropped if the sum is greater than or equal to a predefined drop threshold then the email is considered to be definitely spam and is discarded or a...

  • Page 224

    And this is what the email's recipient will see in the summary of their inbox contents. The individual user could then decide to set up their own filters in the local client to deal with such tagged emails, possibly sending it to a separate folder. Adding x-spam information if an email is determined...

  • Page 225

    Allowed through if this happens. Setup summary to set up dnsbl spam filtering in the smtp alg, the following list summarizes the steps: • specify which dnsbl servers are to be used. There can be multiple and they can act both as backups to each other as well as confirmation of a sender's status. • s...

  • Page 226

    The dnsbl cli command provides a means to control and monitor the operation of the spam filtering module. The dnsbl command on its own without options shows the overall status of all algs. If the name of the smtp alg object on which dnsbl spam filtering is enabled is my_smtp_alg then the output woul...

  • Page 227: 6.2.6. The Pop3 Alg

    6.2.6. The pop3 alg pop3 is a mail transfer protocol that differs from smtp in that the transfer of mail is directly from a server to a user's client software. Pop3 alg options key features of the pop3 alg are: block clear text authentication block connections between client and server that send the...

  • Page 228

    Same server c at the same endpoint ip address, the first connection for a will be lost. The reason is that both clients are trying to establish a pptp tunnel from the same external ip address to the same endpoint. Figure 6.5. Pptp alg usage the pptp alg solves this problem. By using the alg, the tra...

  • Page 229: 6.2.8. The Sip Alg

    Action src interface src network dest interface dest network service nat lan lannet wan all-nets pptp_service pptp alg settings the following settings are available for the pptp alg: name a descriptive name for the alg. Echo timeout idle timeout for echo messages in the pptp tunnel. Idle timeout idl...

  • Page 230

    Registrars a server that handles sip register requests is given the special name of registrar. The registrar server has the task of locating the host where the other client is reachable. The registrar and proxy server are logical entities and may, in fact, reside on the same physical server. Sip med...

  • Page 231

    To understand how to set up sip scenarios with netdefendos, it is important to first understand the sip proxy record-route option. Sip proxies have the record-route option either enabled or disabled. When it is switched on, a proxy is known as a stateful proxy. When record-route is enabled, a proxy ...

  • Page 232

    Protecting proxy and local clients - proxy on the same network as clients the sip session is between a client on the local, protected side of the netdefend firewall and a client which is on the external, unprotected side. The sip proxy is located on the local, protected side of the netdefend firewal...

  • Page 233

    Technique should not be used. The netdefendos sip alg will take care of all nat traversal issues in a sip scenario. The setup steps for this scenario are as follows: 1. Define a sip alg object using the options described above. 2. Define a service object which is associated with the sip alg object. ...

  • Page 234

    Action src interface src network dest interface dest network allow (or nat) lan lannet wan allow wan lan (or core) lannet (or ipwan) the advantage of using record-route is clear since now the destination network for outgoing traffic and the source network for incoming traffic have to include all ip ...

  • Page 235

    3. Define three rules in the ip rule set: • a nat rule for outbound traffic from the local proxy and the clients on the internal network to the remote clients on, for example, the internet. The sip alg will take care of all address translation needed by the nat rule. This translation will occur both...

  • Page 236

    The complexity is increased in this scenario since sip messages flow across three interfaces: the receiving interface from the call initiator, the dmz interface towards the proxy and the destination interface towards the call terminator. This the initial messages exchanges that take place when a cal...

  • Page 237

    • the ip address of the sip proxy must be a globally routable ip address. The netdefend firewall does not support hiding of the proxy on the dmz. • the ip address of the dmz interface must be a globally routable ip address. This address can be the same address as the one used on the external interfa...

  • Page 238

    Action src interface src network dest interface dest network outboundtoproxy nat lan lannet dmz ip_proxy outboundfromproxy allow dmz ip_proxy wan all-nets inboundfromproxy allow dmz ip_proxy core dmz_ip inboundtoproxy allow wan all-nets dmz ip_proxy with record-route disabled, the following ip rules...

  • Page 239: 6.2.9. The H.323 Alg

    Action src interface src network dest interface dest network inboundbypassproxy allow wan all-nets lan lannet 6.2.9. The h.323 alg h.323 is a standard approved by the international telecommunication union (itu) to allow compatibility in video conference transmissions over ip networks. It is used for...

  • Page 240

    Communication. Video and t.120 channels are also called logical channels during negotiation. T.120 a suite of communication and application protocols. Depending on the type of h.323 product, t.120 protocol can be used for application sharing, file transfer as well as for conferencing features such a...

  • Page 241

    A configuration example of both the alg and the rules are presented. The three service definitions used in these scenarios are: • gatekeeper (udp all > 1719) • h323 (h.323 alg, tcp all > 1720) • h323-gatekeeper (h.323 alg, udp > 1719) example 6.4. Protecting phones behind netdefend firewalls in the ...

  • Page 242

    1. Go to rules > ip rules > add > iprule 2. Now enter: • name: h323allowin • action: allow • service: h323 • source interface: any • destination interface: lan • source network: 0.0.0.0/0 (all-nets) • destination network: lannet • comment: allow incoming calls 3. Click ok example 6.5. H.323 with pri...

  • Page 243

    • destination interface: core • source network: 0.0.0.0/0 (all-nets) • destination network: wan_ip (external ip of the firewall) • comment: allow incoming calls to h.323 phone at ip-phone 3. For sat enter translate destination ip address: to new ip address: ip-phone (ip address of phone) 4. Click ok...

  • Page 244

    Web interface outgoing rule: 1. Go to rules > ip rules > add > iprule 2. Now enter: • name: h323allowout • action: allow • service: h323 • source interface: lan • destination interface: any • source network: lannet • destination network: 0.0.0.0/0 (all-nets) • comment: allow outgoing calls 3. Click ...

  • Page 245

    • service: h323 • source interface: lan • destination interface: any • source network: lannet • destination network: 0.0.0.0/0 (all-nets) • comment: allow outgoing calls 3. Click ok incoming rules: 1. Go to rules > ip rules > add > iprule 2. Now enter: • name: h323in • action: sat • service: h323 • ...

  • Page 246

    In this scenario, a h.323 gatekeeper is placed in the dmz of the netdefend firewall. A rule is configured in the firewall to allow traffic between the private network where the h.323 phones are connected on the internal network and to the gatekeeper on the dmz. The gatekeeper on the dmz is configure...

  • Page 247

    • comment: allow incoming communication with the gatekeeper 3. Click ok 1. Go to rules > ip rules > add > iprule 2. Now enter: • name: h323in • action: allow • service: h323-gatekeeper • source interface: lan • destination interface: dmz • source network: lannet • destination network: ip-gatekeeper ...

  • Page 248

    Web interface 1. Go to rules > ip rules > add > iprule 2. Now enter: • name: h323out • action: nat • service: h323-gatekeeper • source interface: lan • destination interface: any • source network: lannet • destination network: 0.0.0.0/0 (all-nets) • comment: allow outgoing communication with a gatek...

  • Page 249

    The head office has placed a h.323 gatekeeper in the dmz of the corporate netdefend firewall. This firewall should be configured as follows: web interface 1. Go to rules > ip rules > add > iprule 2. Now enter: • name: lantogk • action: allow • service: h323-gatekeeper • source interface: lan • desti...

  • Page 250

    • source interface: lan • destination interface: dmz • source network: lannet • destination network: ip-gateway • comment: allow h.323 entities on lannet to call phones connected to the h.323 gateway on the dmz 3. Click ok 1. Go to rules > ip rules > add > iprule 2. Now enter: • name: gwtolan • acti...

  • Page 251

    3. Click ok example 6.11. Configuring remote offices for h.323 if the branch and remote office h.323 phones and applications are to be configured to use the h.323 gatekeeper at the head office, the netdefend firewalls in the remote and branch offices should be configured as follows: (this rule shoul...

  • Page 252: 6.2.10. The Tls Alg

    The communication between "external" phones and the gatekeeper to make sure that it is possible for internal phones to call the external phones that are registered with the gatekeeper. 6.2.10. The tls alg overview transport layer security (tls) is a protocol that provides secure communications over ...

  • Page 253

    Advantages of using netdefendos for tls termination tls can be implemented directly in the server to which clients connect, however, if the servers are protected behind a netdefend firewall, then netdefendos can take on the role of the tls endpoint. Netdefendos then performs tls authentication, encr...

  • Page 254

    6. Optionally, a sat rule can be created to change the destination port for the unencrypted traffic. Alternatively an slb_sat rule can be used to do load balancing (the destination port can also be changed through a custom service object). Urls delivered by servers it should be noted that using netd...

  • Page 255: 6.3.1. Overview

    6.3. Web content filtering 6.3.1. Overview web traffic is one of the biggest sources for security issues and misuse of the internet. Inappropriate surfing habits can expose a network to many security threats as well as legal and regulatory liabilities. Productivity and internet bandwidth can also be...

  • Page 256

    Removing such legitimate code could, at best, cause the web site to look distorted, at worst, cause it to not work in a browser at all. Active content handling should therefore only be used when the consequences are well understood. Example 6.13. Stripping activex and java applets this example shows...

  • Page 257

    */*.Gif good. This will block all files with .Gif as the file name extension. Www.Example.Com bad. This will only block the first request to the web site. Surfing to www.Example.Com/index.Html, for example, will not be blocked. *example.Com/* bad. This will also cause www.Myexample.Com to be blocked...

  • Page 258

    6. Enter */*.Exe in the url textbox 7. Click ok finally, make an exception from the blacklist by creating a whitelist: 1. Go to objects > alg 2. In the table, click on the recently created http alg to view its properties 3. Click the http url tab 4. Now click add and select http alg url from the men...

  • Page 259

    Community, such as a group of university students, often surfs to a limited range of websites. Figure 6.7. Dynamic content filtering flow if the requested web page url is not present in the databases, then the webpage content at the url will automatically be downloaded to d-link's central data wareh...

  • Page 260

    Activation dynamic content filtering is a feature that is enabled by taking out a separate subscription to the service. This is an addition to the normal netdefendos license. Once a subscription is taken out, an http application layer gateway (alg) object should be defined with dynamic content filte...

  • Page 261

    1. Go to objects > alg > add > http alg 2. Specify a suitable name for the alg, for example content_filtering 3. Click the web content filtering tab 4. Select enabled in the mode list 5. In the blocked categories list, select search sites and click the >> button. 6. Click ok then, create a service o...

  • Page 262

    Easier to evaluate if the goals of site blocking are being met. Example 6.16. Enabling audit mode this example is based on the same scenario as the previous example, but now with audit mode enabled. Command-line interface first, create an http application layer gateway (alg) object: gw-world:/> add ...

  • Page 263

    Manually propose a new classification of sites. This mechanism can be enabled on a per-http alg level, which means that you can choose to enable this functionality for regular users or for a selected user group only. If reclassification is enabled and a user requests a web site which is disallowed, ...

  • Page 264

    Of each category. Category 1: adult content a web site may be classified under the adult content category if its content includes the description or depiction of erotic or sexual acts or sexually oriented material such as pornography. Exceptions to this are web sites that contain information relatin...

  • Page 265

    • www.Flythere.Nu • www.Reallycheaptix.Com.Au category 6: shopping a web site may be classified under the shopping category if its content includes any form of advertisement of goods or services to be exchanged for money, and may also include the facilities to perform that transaction online. Includ...

  • Page 266

    Computer game related software, or playing or participating in online games. Examples might be: • www.Gamesunlimited.Com • www.Gameplace.Com category 11: investment sites a web site may be classified under the investment sites category if its content includes information, services or facilities pert...

  • Page 267

    • www.Political.Com category 16: sports a web site may be classified under the sports category if its content includes information or instructions relating to recreational or professional sports, or reviews on sporting events and sports scores. Examples might be: • www.Sportstoday.Com • www.Soccerba...

  • Page 268

    Category 21: health sites a web site may be classified under the health sites category if its content includes health related information or services, including sexuality and sexual health, as well as support groups, hospital and surgical information and medical journals. Examples might be: • www.Th...

  • Page 269

    • highschoolessays.Org • www.Learn-at-home.Com category 27: advertising a web site may be classified under the advertising category if its main focus includes providing advertising related information or services. Examples might be: • www.Admessages.Com • www.Tripleclick.Com category 28: drugs/alcoh...

  • Page 270

    Category 32: non-managed unclassified sites and sites that do not fit one of the other categories will be placed in this category. It is unusual to block this category since this could result in most harmless urls being blocked. 6.3.4.4. Customizing html pages dynamic web content filtering make use ...

  • Page 271

    Tip: saving changes in the above example, more than one html file can be edited in a session but the save button should be pressed to save any edits before beginning editing on another file. Uploading with scp it is possible to upload new http banner files using scp. The steps to do this are: 1. Sin...

  • Page 272: 6.4. Anti-Virus Scanning

    6.4. Anti-virus scanning 6.4.1. Overview the netdefendos anti-virus module protects against malicious code carried in file downloads. Files may be downloaded as part of a web-page in an http transfer, in an ftp download, or perhaps as an attachment to an email delivered through smtp. Malicious code ...

  • Page 273

    Types of file downloads scanned as described above, anti-virus scanning is enabled on a per alg basis and can scan file downloads associated with the http, ftp, smtp and pop3 algs. More specifically: • any uncompressed file type transferred through these algs can be scanned. • if the download has be...

  • Page 274: 6.4.6. Anti-Virus Options

    6.4.4. The signature database safestream netdefendos anti-virus scanning is implemented by d-link using the "safestream" virus signature database. The safestream database is created and maintained by kaspersky, a company which is a world leader in the field of virus detection. The database provides ...

  • Page 275

    The excluded list is checked. 3. Compression ratio limit when scanning compressed files, netdefendos must apply decompression to examine the file's contents. Some types of data can result in very high compression ratios where the compressed file is a small fraction of the original uncompressed file ...

  • Page 276

    3. This reconfiguration causes a failover so the passive unit becomes the active unit. 4. When the update is completed, the newly active unit also downloads the files for the update and performs a reconfiguration. 5. This second reconfiguration causes another failover so the passive unit reverts bac...

  • Page 277

    Web interface a. First, create an http alg object: 1. Go to objects > alg > add > http alg 2. Specify a suitable name for the alg, for instance anti_virus 3. Click the antivirus tab 4. Select protect in the mode dropdown list 5. Click ok b. Then, create a service object using the new http alg: 1. Go...

  • Page 278: 6.5.1. Overview

    6.5. Intrusion detection and prevention 6.5.1. Overview intrusion definition computer servers can sometimes have vulnerabilities which leave them exposed to attacks carried by network traffic. Worms, trojans and backdoor exploits are examples of such attacks which, if successful, can potentially com...

  • Page 279

    • maintenance idp maintenance idp is the base idp system included as standard with the netdefend dfl 210, 800, 1600 and 2500. Maintenance idp is a simplified idp that gives basic protection against idp attacks. It is upgradeable to the higher level and more comprehensive advanced idp which is discus...

  • Page 280: 6.5.3. Idp Rules

    A new, updated signature database is downloaded automatically by netdefendos system at a configurable interval. This is done via an http connection to the d-link server network which delivers the latest signature database updates. If the server's signature database has a newer version than the curre...

  • Page 281

    Http normalization each idp rule has a section of settings for http normalization. This allows the administrator to choose the actions that should be taken when idp finds inconsistencies in the uris embedded in incoming http requests. Some server attacks are based on creating uris with sequences tha...

  • Page 282

    Aimed at evading idp mechanisms. It exploits the fact that in a tcp/ip data transfer, the data stream must often be reassembled from smaller pieces of data because the individual pieces either arrive in the wrong order or are fragmented in some way. Insertions or evasions are designed to exploit thi...

  • Page 283

    Signatures in order for idp to correctly identify an attack, it uses a profile of indicators, or pattern, associated with different types of attack. These predefined patterns, also known as signatures, are stored in a local netdefendos database and are used by the idp module to analyze traffic for a...

  • Page 284

    Least possible number of signatures. Specifying signature groups idp signature groups fall into a three level hierarchical structure. The top level of this hierarchy is the signature type, the second level the category and the third level the sub-category. The signature group called policy_db_mssql ...

  • Page 285: 6.5.7. Idp Actions

    Ids_http* and ips_http* idp groups would be appropriate for protecting an http server. Idp traffic scanning creates an additional load on the hardware that in most cases should not noticeably degrade performance. Using too many signatures during scanning can make the load on the firewall hardware un...

  • Page 286

    Example 6.20. Configuring an smtp log receiver in this example, an idp rule is configured with an smtp log receiver. Once an idp event occurs, the rule is triggered. At least one new event occurs within the hold time of 120 seconds, thus reaching the log threshold level (at least 2 events have occur...

  • Page 287

    The firewall on the wan interface as illustrated below. An idp rule called idpmailsrvrule will be created, and the service to use is the smtp service. Source interface and source network defines where traffic is coming from, in this example the external network. The destination interface and destina...

  • Page 288

    • destination network: ip_mailserver • click ok specify the action: an action is now defined, specifying what signatures the idp should use when scanning data matching the rule, and what netdefendos should do when a possible intrusion is detected. In this example, intrusion attempts will cause the c...

  • Page 289: 6.6.1. Overview

    6.6. Denial-of-service attack prevention 6.6.1. Overview by embracing the internet, enterprises experience new business opportunities and growth. The enterprise network and the applications that run over it are business critical. Not only can a company reach a larger number of customers via the inte...

  • Page 290: Boink And Nestea

    Intended victim. "jolt" is simply a purpose-written program for generating such packets on operating systems whose ping commands refuse to generate oversized packets. The triggering factor is that the last fragment makes the total packet size exceed 65535 bytes, which is the highest number that a 16...

  • Page 291

    • by stripping the urg bit by default from all tcp segments traversing the system (configurable via advanced settings > tcp > tcpurg). Winnuke attacks will usually show up in netdefendos logs as normal drops with the name of the rule in your policy that disallowed the connection attempt. For connect...

  • Page 292: 6.6.9. The Jolt2 Attack

    6.6.8. Tcp syn flood attacks tcp syn flood attacks work by sending large amounts of tcp syn packets to a given port and then not responding to syn acks sent in response. This will tie up local tcp stack resources on the victim's web server so that it is unable to respond to more syn packets until th...

  • Page 293

    Attacks on victim sites. These attacks typically exhaust bandwidth, router processing capacity, or network stack resources, breaking network connectivity to the victims. Although recent ddos attacks have been launched from both private corporate and public institutional systems, hackers tend to ofte...

  • Page 294

    6.7. Blacklisting hosts and networks overview netdefendos implements a blacklist of host or network ip addresses which can be utilized to protect against traffic coming from specific internet sources. Certain netdefendos subsystems have the ability to optionally blacklist a host or network when cert...

  • Page 295

    Blacklisted, it still does not prevent netdefendos mechanisms such as threshold rules from dropping or denying connections from that source. What whitelisting does is prevent a source being added to a blacklist if that is the action a rule has specified. For further details on usage see section 6.5....

  • Page 296

    6.7. Blacklisting hosts and networks chapter 6. Security mechanisms 296.

  • Page 297: 7.1. Overview

    Chapter 7. Address translation this chapter describes netdefendos address translation capabilities. • overview, page 297 • nat, page 298 • nat pools, page 303 • sat, page 306 7.1. Overview the ability of netdefendos to change the ip address of packets as they pass through the netdefend firewall is k...

  • Page 298: 7.2. Nat

    7.2. Nat dynamic network address translation (nat) provides a mechanism for translating original source ip addresses to a different address. Outgoing packets then appear to come from a different ip address and incoming packets back to that address have their ip address translated back to the origina...

  • Page 299

    Tip: use nat pools to get around the connection limit the connection maximum per unique ip pair is normally adequate for all but the most extreme scenarios. However, to increase the number of nat connections that can exist between the netdefend firewall and a particular external host ip, the netdefe...

  • Page 300

    4. Netdefendos receives the packet and compares it to its list of open connections. Once it finds the connection in question, it restores the original address and forwards the packet. 195.55.66.77:80 => 192.168.1.5:1038 5. The original sender now receives the response. Example 7.1. Adding a nat rule...

  • Page 301

    This means that: • an internal machine can communicate with several external servers using the same ip protocol. • an internal machine can communicate with several external servers using different ip protocols. • several internal machines can communicate with different external servers using the sam...

  • Page 302

    Netdefendos is set up with nat rules in the ip rule set so it takes communication traffic coming from the client and nats it back out onto the internet. Communication with the client is with the pptp protocol but the pptp tunnel from the client terminates at the firewall. When this traffic is relaye...

  • Page 303: 7.3. Nat Pools

    7.3. Nat pools overview as discussed in section 7.2, “nat”, nat provides a way to have multiple internal clients and hosts with unique private internal ip addresses communicate to remote hosts through a single external public ip address. When multiple public external ip addresses are available then ...

  • Page 304

    Stateless nat pools the stateless option means that no state table is maintained and the external ip address chosen for each new connection is the one that has the least connections already allocated to it. This means two connections between one internal host to the same external host may use two di...

  • Page 305

    Web interface a. First create an object in the address book for the address range: 1. Go to objects > address book > add > ip address 2. Specify a suitable name for the ip range nat_pool_range 3. Enter 10.6.13.10-10.16.13.15 in the ip address textbox (a network such as 10.6.13.0/24 could be used her...

  • Page 306: 7.4. Sat

    7.4. Sat netdefendos can translate entire ranges of ip addresses and/or ports. Such translations are transpositions, each address or port is mapped to a corresponding address or port in the new range, rather than translating them all to the same address or port. In netdefendos this functionality is ...

  • Page 307

    Sourcenetwork=all-nets destinationinterface=core destinationnetwork=wan_ip sattranslate=destinationip sattranslatetoip=10.10.10.5 name=sat_http_to_dmz then create a corresponding allow rule: gw-world:/main> add iprule action=allow service=http sourceinterface=any sourcenetwork=all-nets destinationin...

  • Page 308

    These two rules allow us to access the web server via the netdefend firewall's external ip address. Rule 1 states that address translation can take place if the connection has been permitted, and rule 2 permits the connection. Of course, we also need a rule that allows internal machines to be dynami...

  • Page 309

    In order for external users to access the web server, they must be able to contact it using a public address. In this example, we have chosen to translate port 80 on the netdefend firewall's external address to port 80 on the web server: # action src iface src net dest iface dest net parameters 1 sa...

  • Page 310

    • the reply arrives and both address translations are restored: 195.55.66.77:80 => 10.0.0.3:1038 in this way, the reply arrives at pc1 from the expected address. Another possible solution to this problem is to allow internal clients to speak directly to 10.0.0.2 and this would completely avoid all t...

  • Page 311

    Address=195.55.66.77-195.55.66.81 now, create another object for the base of the web server ip addresses: gw-world:/> add address ip4address wwwsrv_priv_base address=10.10.10.5 publish the public ip addresses on the wan interface using arp publish. One arp item is needed for every ip address: gw-wor...

  • Page 312

    Create a sat rule for the translation: 1. Go to rules > ip rules > add > iprule 2. Specify a suitable name for the rule, for example sat_http_to_dmz 3. Now enter: • action: sat • servce: http • source interface:any • source network: all-nets • destination interface: wan • destination network: wwwsrv...

  • Page 313: 7.4.4. Port Translation

    Note when all-nets is the destination, all-to-one mapping is always done. 7.4.4. Port translation port translation (pat) (also known as port address translation) can be used to modify the source or destination port. # action src iface src net dest iface dest net parameters 1 sat any all-nets wan www...

  • Page 314

    The phrase "each address" above means that two sat rules can be in effect at the same time on the same connection, provided that one is translating the sender address whilst the other is translating the destination address. # action src iface src net dest iface dest net parameters 1 sat any all-nets...

  • Page 315

    We will now try moving the nat rule between the sat and fwdfast rules: # action src iface src net dest iface dest net parameters 1 sat any all-nets core wan_ip http setdest wwwsrv 80 2 sat lan wwwsrv any all-nets 80 -> all setsrc wan_ip 80 3 nat lan lannet any all-nets all 4 fwdfast any all-nets cor...

  • Page 316

    7.4.7. Sat and fwdfast rules chapter 7. Address translation 316.

  • Page 317: 8.1. Overview

    Chapter 8. User authentication this chapter describes how netdefendos implements user authentication. • overview, page 317 • authentication setup, page 319 • customizing html pages, page 333 8.1. Overview in situations where individual users connect to protected resources through the netdefend firew...

  • Page 318

    • changed on a regular basis such as every three months. 8.1. Overview chapter 8. User authentication 318.

  • Page 319: 8.2. Authentication Setup

    8.2. Authentication setup 8.2.1. Setup summary the following list summarizes the steps for user authentication setup with netdefendos: • set up a database of users, each with a username/password combination. This can exist locally in a netdefendos user db object, or remotely on a radius server and w...

  • Page 320

    Radius with netdefendos netdefendos acts as a radius client, sending user credentials and connection parameter information as a radius message to a nominated radius server. The server processes the requests and sends back a radius message to accept or deny them. One or more external servers can be d...

  • Page 321

    Option in the netdefendos ldap server setup which has special consideration with active directory and that is the name attribute. This should be set to samaccountname. Defining an ldap server one or more named ldap server objects can be defined in netdefendos. These objects tell netdefendos which ld...

  • Page 322

    • name attribute the name attribute is the id of the data field on the ldap server that contains the username. The netdefendos default value for this is uid which is correct for most unix based servers. If using microsoft active directory this should be set to samaccountname (which is not case sensi...

  • Page 323

    • base object defines where in the ldap server tree search for user accounts shall begin. The users defined on an ldap server database are organized into a tree structure. The base object specifies where in this tree the relevant users are located. Specifying the base object has the effect of speedi...

  • Page 324

    Bind request authentication ldap server authentication is automatically configured to work using ldap bind request authentication. This means that authentication succeeds if successful connection is made to the ldap server. Individual clients are not distinguished from one another. Ldap server refer...

  • Page 325

    A specific ldap server that is defined in netdefendos for authentication can be shown with the command: gw-world:/> show ldapdatabase the entire contents of the database can be displayed with the command: gw-world:/> show ldapdatabase ldap authentication and ppp when using a ppp based client for ppt...

  • Page 326

    This id must be different from the default password attribute (which is usually userpassword for most ldap servers). A suggestion is to use the description field in the ldap database. • in order for the server to return the password in the database field with the id specified, the ldap administrator...

  • Page 327

    • interface the source interface on which the connections to be authenticated will arrive. • source ip the source network from which new connections will arrive. • authentication source - this specifies that authentication is to be done against one of the following: • the local database defined with...

  • Page 328: 8.2.7. Http Authentication

    An authentication rule can specify how multiple logins are handled where more than one user from different source ip addresses try to login with the same username. The possible options are: • allow multiple logins so that more than one client can use the same username/password combination. • allow o...

  • Page 329

    Changing the management webui port http authentication will collide with the webui's remote management service which also uses tcp port 80. To avoid this, the webui port number should be changed before configuring authentication. Do this by going to remote management > advanced settings in the webui...

  • Page 330

    Authentication page we must add a sat rule and its associated allow rule. The rule set will now look like this: # action src interface src network dest interface dest network service 1 allow lan lannet core lan_ip http-all 2 nat lan trusted_users wan all-nets http-all 3 nat lan lannet wan all-nets d...

  • Page 331

    Example 8.1. Creating an authentication user group in the example of an authentication address object in the address book, a user group "users" is used to enable user authentication on "lannet". This example shows how to configure the user group in the netdefendos database. Web interface step a 1. G...

  • Page 332

    • destination network lan_ip 3. Click ok b. Set up the authentication rule 1. Go to user authentication > user authentication rules > add > user authentication rule 2. Now enter: • name: httplogin • agent: http • authentication source: local • interface: lan • originator ip: lannet 3. For local user...

  • Page 333

    F. Shared secret: enter a text string here for basic encryption of the radius messages g. Confirm secret: retype the string to confirm the one typed above 3. Click ok 8.3. Customizing html pages user authentication makes use of a set of html files to present information to the user during the authen...

  • Page 334

    • %ipaddr% - the ip address which is being browsed from. • %reason% - the reason that access was denied. • - the web page url for redirects. The %redirurl% parameter in certain banner web pages, the parameter %redirurl% appears. This is a placeholder for the original url which was requested before t...

  • Page 335

    2. A new auth banner files object must exist which the edited file(s) is uploaded to. If the object is called ua_html, the cli command to create this object is: gw-world:/> add httpauthbanners ua_html this creates an object which contains a copy of all the default user auth banner files. 3. The modi...

  • Page 336

    8.3. Customizing html pages chapter 8. User authentication 336.

  • Page 337: Chapter 9. Vpn

    Chapter 9. Vpn this chapter describes the virtual private network (vpn) functionality in netdefendos. • overview, page 337 • vpn quick start, page 341 • ipsec components, page 351 • ipsec tunnels, page 365 • pptp/l2tp, page 383 • ca server access, page 392 • vpn troubleshooting, page 395 9.1. Overvi...

  • Page 338: 9.1.2. Vpn Encryption

    2. Client to lan connection - where many remote clients need to connect to an internal network over the internet. In this case, the internal network is protected by the netdefend firewall to which the client connects and the vpn tunnel is set up between them. 9.1.2. Vpn encryption encryption of vpn ...

  • Page 339: 9.1.4. Key Distribution

    • restricting access through the vpn to needed services only, since mobile computers are vulnerable. • creating dmzs for services that need to be shared with other companies through vpns. • adapting vpn access policies for different groups of users. • creating key distribution policies. Endpoint sec...

  • Page 340

    “the tls alg”. 9.1.5. The tls alternative for vpn chapter 9. Vpn 340

  • Page 341: 9.2. Vpn Quick Start

    9.2. Vpn quick start overview later sections in this chapter will explore vpn components in detail. To help put those later sections in context, this section is a quick start summary of the steps needed for vpn setup. It outlines the individual steps in setting up vpns for the most common scenarios....

  • Page 342

    9.2.1. Ipsec lan to lan with pre-shared keys 1. Create a pre-shared key object. 2. Optionally create a new ike algorithms object and/or an ipsec algorithms object if the default algorithm proposal lists do not provide a set of algorithms that are acceptable to the tunnel remote end point. This will ...

  • Page 343

    Action src interface src network dest interface dest network service allow ipsec_tunnel remote_net lan lannet all the service used in these rules is all but it could be a predefined service. 6. Define a new netdefendos route which specifies that the vpn tunnel ipsec_tunnel is the interface to use fo...

  • Page 344

    Considered adequate. Two self-signed certificates are required and the same two are used at either end of the tunnel but their usage is reversed. In other words: one certificate is used as the root certificate at one end, call it side a, and as the host certificate at the other end, call it side b. ...

  • Page 345

    The group string for a user can be specified if its group's access is to be restricted to certain source networks. Group can be specified (with the same text string) in the authentication section of an ip object. If that ip object is then used as the source network of a rule in the ip rule set, that...

  • Page 346

    • create a config mode pool object (there can only be one associated with a netdefendos installation) and in it specify the address range. • enable the ike config mode option in the ipsec tunnel object ipsec_tunnel. 2. If client ip addresses are to be retrieved through dhcp: • create an ip pool obje...

  • Page 347

    Note: the system time and date should be correct the netdefendos date and time should be set correctly since certificates have an expiry date and time. Also review section 9.6, “ca server access”, which describes important considerations for certificate validation. 9.2.5. L2tp roaming clients with p...

  • Page 348

    • set outer interface filter to ipsec_tunnel. • set outer server ip to ip_ext. • select the microsoft point-to-point encryption allowed. Since ipsec encryption is used this can be set to be none only, otherwise double encryption will degrade throughput. • set ip pool to l2tp_pool. • enable proxy arp...

  • Page 349

    2. Load a gateway certificate and root certificate into netdefendos. 3. When setting up the ipsec tunnel object, specify the certificates to use under authentication. This is done by: a. Enable the x.509 certificate option. B. Select the gateway certificate. C. Add the root certificate to use. 4. If...

  • Page 350

    3. Define a user authentication rule, this is almost identical to l2tp: agent auth source src network interface client source ip ppp local all-nets pptp_tunnel all-nets (0.0.0.0/0) 4. Now set up the ip rules in the ip rule set: action src interface src network dest interface dest network service all...

  • Page 351: 9.3. Ipsec Components

    9.3. Ipsec components 9.3.1. Overview internet protocol security (ipsec) is a set of protocols defined by the internet engineering task force (ietf) to provide ip security at the network layer. An ipsec based vpn is made up of two parts: • internet key exchange protocol (ike) • ipsec protocols (ah/e...

  • Page 352

    Describing the incoming traffic, and the other the outgoing. In cases where esp and ah are used in conjunction, four sas will be created. Ike negotiation the process of negotiating session parameters consists of a number of phases and modes. These are described in detail in the below sections. The f...

  • Page 353

    However, since we do not want to publish to much of the negotiation in plaintext, we first agree upon a way of protecting the rest of the ike negotiation. This is done, as described in the previous section, by the initiator sending a proposal-list to the responder. When this has been done, and the r...

  • Page 354

    This way, an eavesdropper will only see encrypted traffic going from one of vpn endpoint to another. In transport mode, the traffic will not be tunneled, and is hence not applicable to vpn tunnels. It can be used to secure a connection from a vpn client directly to the netdefend firewall, for exampl...

  • Page 355

    Ike encryption this specifies the encryption algorithm used in the ike negotiation, and depending on the algorithm, the size of the encryption key used. The algorithms supported by netdefendos ipsec are: • aes • blowfish • twofish • cast128 • 3des • des des is only included to be interoperable with ...

  • Page 356

    Pfs dh group this specifies the diffie-hellman group to use with pfs. The available dh groups are discussed below. Ipsec dh group this specifies the diffie-hellman group to use for ipsec communication. The available dh groups are discussed below in the section titled diffie-hellman groups. Ipsec enc...

  • Page 357: 9.3.3. Ike Authentication

    By netdefendos are as follows: • dh group 1 (768-bit) • dh group 2 (1024-bit) • dh group 5 (1536-bit) all these ha groups are available for use with ike, ipsec and pfs. 9.3.3. Ike authentication manual keying the "simplest" way of configuring a vpn is by using a method called manual keying. This is ...

  • Page 358

    One thing that has to be considered when using pre-shared keys is key distribution. How are the pre-shared keys distributed to remote vpn clients and firewalls? This is a major issue, since the security of a psk system is based on the psks being secret. Should one psk be compromised, the configurati...

  • Page 359: 9.3.5. Nat Traversal

    Ah uses a cryptographic hash function to produce a mac from the data in the ip packet. This mac is then transmitted with the packet, allowing the remote endpoint to verify the integrity of the original ip packet, making sure the data has not been tampered with on its way through the internet. Apart ...

  • Page 360

    Achieving nat detection to achieve nat detection both ipsec peers send hashes of their own ip addresses along with the source udp port used in the ike negotiations. This information is used to see whether the ip address and source port each peer uses is the same as what the other peer sees. If the s...

  • Page 361

    There are two types of proposal lists, ike proposal lists and ipsec proposal lists. Ike lists are used during ike phase-1 (ike security negotiation), while ipsec lists are using during ike phase-2 (ipsec security negotiation). Several algorithm proposal lists are already defined by default in netdef...

  • Page 362: 9.3.7. Pre-Shared Keys

    9.3.7. Pre-shared keys pre-shared keys are used to authenticate vpn tunnels. The keys are secrets that are shared by the communicating parties before communication takes place. To communicate, both parties prove that they know the secret. The security of a shared secret depends on how "good" a passp...

  • Page 363

    9.3.8. Identification lists when certificates are used as authentication method for ipsec tunnels, the netdefend firewall will accept all remote devices or vpn clients that are capable of presenting a certificate signed by any of the trusted certificate authorities. This can be a potential problem, ...

  • Page 364

    Web interface first create an identification list: 1. Go to objects > vpn objects > id list > add > id list 2. Enter a name for the list, for example myidlist 3. Click ok then, create an id: 1. Go to objects > vpn objects > ike id list > add > id list 2. Select myidlist 3. Enter a name for the id, f...

  • Page 365: 9.4. Ipsec Tunnels

    9.4. Ipsec tunnels 9.4.1. Overview an ipsec tunnel defines an endpoint of an encrypted tunnel. Each ipsec tunnel is interpreted as a logical interface by netdefendos, with the same filtering, traffic shaping and configuration capabilities as regular interfaces. Remote initiation of tunnel establishm...

  • Page 366: 9.4.3. Roaming Clients

    Ipsec tunnel quick start this section covers ipsec tunnels in some detail. A quick start checklist of setup steps for these protocols in typical scenarios can be found in the following sections: • section 9.2.1, “ipsec lan to lan with pre-shared keys”. • section 9.2.2, “ipsec lan to lan with certifi...

  • Page 367

    The algorithm proposal lists that are pre-configured in netdefendos. Psk based client tunnels the following example shows how a psk based tunnel can be set up. Example 9.4. Setting up a psk based vpn tunnel for roaming clients this example describes how to configure an ipsec tunnel at the head offic...

  • Page 368

    Example 9.5. Setting up a self-signed certificate based vpn tunnel for roaming clients this example describes how to configure an ipsec tunnel at the head office netdefend firewall for roaming clients that connect to the office to gain remote access. The head office network uses the 10.0.1.0/24 netw...

  • Page 369

    5. Under the routing tab: • enable the option: dynamically add route to the remote network when a tunnel is established. 6. Click ok e. Finally configure the ip rule set to allow traffic inside the tunnel. Tunnels based on ca server certificates setting up client tunnels using a ca issued certificat...

  • Page 370

    • remote endpoint: (none) • encapsulation mode: tunnel 3. For algorithms enter: • ike algorithms: medium or high • ipsec algorithms: medium or high 4. For authentication enter: • choose x.509 certificates as the authentication method • root certificate(s): select your ca server root certificate impo...

  • Page 371

    Example 9.7. Setting up config mode in this example, the config mode pool object is enabled by associating with it an already configured ip pool object called ip_pool1. Web interface 1. Go to objects > vpn objects > ike config mode pool 2. The config mode pool object properties web page now appears ...

  • Page 372

    This example shows how to manually setup and specify an ldap server. Command-line interface gw-world:/> add ldapserver host=192.168.101.146 username=myusername password=mypassword port=389 web interface 1. Go to objects > vpn objects > ldap > add > ldap server 2. Now enter: • ip address: 192.168.101...

  • Page 373

    Complete ikesnoop command options can be found in the cli reference guide. The client and the server the two parties involved in the tunnel negotiation are referred to in this section as the client and server. In this context, the word "client" is used to refer to the device which is the initiator o...

  • Page 374

    Life type : kilobytes life duration : 50000 transform 4/4 transform id : ike encryption algorithm : 3des-cbc hash algorithm : sha authentication method : pre-shared key group description : modp 1024 life type : seconds life duration : 43200 life type : kilobytes life duration : 50000 vid (vendor id)...

  • Page 375

    Ikesnoop: sending ike packet to 192.168.0.10:500 exchange type : identity protection (main mode) isakmp version : 1.0 flags : cookies : 0x6098238b67d97ea6 -> 0x5e347cb76e95a message id : 0x00000000 packet length : 224 bytes # payloads : 8 payloads: sa (security association) payload data length : 52 ...

  • Page 376

    Packet length : 220 bytes # payloads : 4 payloads: ke (key exchange) payload data length : 128 bytes nonce (nonce) payload data length : 16 bytes nat-d (nat detection) payload data length : 16 bytes nat-d (nat detection) payload data length : 16 bytes step 4. Server sends key exchange data the serve...

  • Page 377

    Explanation of above values flags: e means encryption (it is the only flag used). Id: identification of the client the notification field is given as initial contact to indicate this is not a re-key. Step 6. Server id response the server now responds with its own id. Ikesnoop: sending ike packet to ...

  • Page 378

    Transform id : rijndael (aes) key length : 128 authentication algorithm : hmac-sha-1 sa life type : seconds sa life duration : 21600 sa life type : kilobytes sa life duration : 50000 encapsulation mode : tunnel transform 3/4 transform id : blowfish key length : 128 authentication algorithm : hmac-md...

  • Page 379

    Packet length : 156 bytes # payloads : 5 payloads: hash (hash) payload data length : 16 bytes sa (security association) payload data length : 56 bytes doi : 1 (ipsec doi) proposal 1/1 protocol 1/1 protocol id : esp spi size : 4 spi value : 0xafba2d15 transform 1/1 transform id : rijndael (aes) key l...

  • Page 380

    Tunnels if the latter is changed. This linkage is broken once ipsec max rules is altered manually so that subsequent changes to ipsec max tunnels will not cause an automatic change in ipsec max rules. Default: 4 times the license limit of ipsec max tunnels ipsec max tunnels specifies the total numbe...

  • Page 381

    When the signature of a user certificate is verified, netdefendos looks at the issuer name field in the user certificate to find the ca certificate the certificate was signed by. The ca certificate may in turn be signed by another ca, which may be signed by another ca, and so on. Each certificate wi...

  • Page 382

    This setting is used with ikev1 only. Default: 2 (in other words, 2 x 10 = 20 seconds) dpd expire time the length of time in seconds for which dpd messages will be sent to the peer. If the peer has not responded to messages during this time it is considered to be dead. In other words, the length of ...

  • Page 383: 9.5. Pptp/l2Tp

    9.5. Pptp/l2tp the access by a client using a modem link over dial-up public switched networks, possibly with an unpredictable ip address, to protected networks via a vpn poses particular problems. Both the pptp and l2tp protocols provide two different means of achieving vpn access from remote clien...

  • Page 384: 9.5.2. L2Tp Servers

    Tcp port 1723 and/or ip protocol 47 before the pptp connection can be made to the netdefend firewall. Examining the log can indicate if this problem occurred, with a log message of the following form appearing: error ppp lcp_negotiation_stalled ppp_terminated example 9.10. Setting up a pptp server t...

  • Page 385

    Example 9.11. Setting up an l2tp server this example shows how to setup a l2tp network server. The example assumes that you have created some address objects in the address book. You will have to specify the ip address of the l2tp server interface, an outer ip address (that the l2tp server should li...

  • Page 386

    2. Enter a suitable name for the user database, for example userdb 3. Go to user authentication > local user databases > userdb > add > user 4. Now enter: • username: testuser • password: mypassword • confirm password: mypassword 5. Click ok now we will setup the ipsec tunnel, which will later be us...

  • Page 387

    Gw-world:/> add interface l2tpserver l2tp_tunnel ip=lan_ip interface=l2tp_ipsec serverip=wan_ip ippool=l2tp_pool tunnelprotocol=l2tp allowedroutes=all-nets proxyarpinterfaces=lan web interface 1. Go to interfaces > l2tp servers > add > l2tpserver 2. Enter a name for the l2tp tunnel, for example l2tp...

  • Page 388

    First, change the current category to be the main ip rule set: gw-world:/> cc ipruleset main now, add the ip rules: gw-world:/main> add iprule action=allow service=all_services sourceinterface=l2tp_tunnel sourcenetwork=l2tp_pool destinationinterface=any destinationnetwork=all-nets name=allowl2tp gw-...

  • Page 389: 9.5.4. Pptp/l2Tp Clients

    Pass l2tp traffic sent to the netdefend firewall directly to the l2tp server without consulting the rule set. Default: enabled pptp before rules pass pptp traffic sent to the netdefend firewall directly to the pptp server without consulting the rule set. Default: enabled max ppp resends the maximum ...

  • Page 390

    Specified gateway. Authentication • username - specifies the username to use for this pptp/l2tp interface. • password - specifies the password for the interface. • authentication - specifies which authentication protocol to use. • mppe - specifies if microsoft point-to-point encryption is used and w...

  • Page 391

    9.5.4. Pptp/l2tp clients chapter 9. Vpn 391.

  • Page 392: 9.6. Ca Server Access

    9.6. Ca server access overview where certificates are used, the two sides of a vpn tunnel exchange their certificates during the tunnel setup negotiation and either may then try to validate the received certificate by accessing a ca server. A certificate contains a url (the crl distribution point) w...

  • Page 393

    3. The ca server is a commercial server on the public internet. In this, the simplest case, public dns servers will resolve the fqdn. The only requirement is that netdefendos will need to have at least one public dns server address configured to resolve the fqdns in the certificates it receives. • i...

  • Page 394

    As explained previously, the address of the private ca server must be resolvable through public dns servers for certificate validation requests coming from the public internet. If the certificate queries are coming only from the netdefend firewall and the ca server is on the internal side of the fir...

  • Page 395: 9.7. Vpn Troubleshooting

    9.7. Vpn troubleshooting this section deals with how to troubelshoot the common problems that are found with vpn. 9.7.1. General troubleshooting in all types of vpns some basic troubleshooting checks can be made: • check that all ip addresses have been specified correctly. • check that all pre-share...

  • Page 396

    If certificates have been used in a vpn solution then the following should be looked at as a source of potential problems: • check that the correct certificates have been used for the right purposes. • check that the certificate .Cer and .Key files have the same filename. For example, my_cert.Key an...

  • Page 397

    Once issued, an icmp ping can then be sent to the netdefend firewall from the remote end of the tunnel. This will cause ikesnoop to output details of the tunnel setup negotiation to the console and any algorithm proposal list incompatibilities can be seen. If there are multiple tunnels in a setup or...

  • Page 398

    To set the lifetime in kb for the ike phase, only seconds. • if the negotiation fails during phase-2 – ipsec the ipsec proposal list does not match. Double check that the ipsec proposal list matches that of the remote side. You can use the same method described above of using ikesnoop from when the ...

  • Page 399: 9.7.6. Specific Symptoms

    An investigation as to why the tunnel only went down from one side is recommended. It could be that dpd and/or keep-alive is only used on one side. Another possible cause could be that even though it has received a delete packet, it has not deleted/removed the tunnel. 4. Payload_malformed this probl...

  • Page 400

    Problem even though xauth is not used. 1. The tunnel can only be initiated from one side this is a common problem and is due to a mismatch of the size in local or remote network and/or the lifetime settings on the proposal list(s). To troubleshoot this you need to examine the settings for the local ...

  • Page 401

    9.7.6. Specific symptoms chapter 9. Vpn 401.

  • Page 402: 10.1. Traffic Shaping

    Chapter 10. Traffic management this chapter describes how netdefendos can manage network traffic. • traffic shaping, page 402 • idp traffic shaping, page 419 • threshold rules, page 424 • server load balancing, page 426 10.1. Traffic shaping 10.1.1. Overview qos with tcp/ip a weakness of tcp/ip is t...

  • Page 403

    Traffic shaping objectives traffic shaping operates by measuring and queuing ip packets with respect to a number of configurable parameters. The objectives are: • applying bandwidth limits and queuing packets that exceed configured limits, then sending them later when bandwidth demands are lower. • ...

  • Page 404

    Needed in an isp scenario where individual pipes are allocated to each client. Pipe rules pipe rules make up the pipe rule set. Each rule is defined much like other netdefendos policies: by specifying the source/destination interface/network as well as the service to which the rule is to apply. Once...

  • Page 405

    It is important to understand that traffic shaping will not work with connection that are established because of a fwdfast rule in the netdefendos ip rule set. The reason for this is that traffic shaping is implemented based on the netdefendos state engine and a fwdfast ip rule does not set up a con...

  • Page 406

    Pass through the std-in pipe. Command-line interface gw-world:/> add piperule returnchain=std-in sourceinterface=lan sourcenetwork=lannet destinationinterface=wan destinationnetwork=all-nets service=all_services name=outbound web interface 1. Go to traffic management > traffic shaping > add > pipe r...

  • Page 407

    Example 10.2. Limiting bandwidth in both directions create a second pipe for outbound traffic: command-line interface gw-world:/> add pipe std-out limitkbpstotal=2000 web interface 1. Go to traffic management > traffic shaping > pipes > add > pipe 2. Specify a name for the pipe, for example std-out ...

  • Page 408: 10.1.6. Precedences

    This is not a bandwidth guarantee for web browsing but it is a 125 kbps bandwidth guarantee for everything except web browsing. For web browsing the normal rules of first-come, first-forwarded will apply when competing for bandwidth. This may mean 125 kbps, but it may also mean much slower speed if ...

  • Page 409

    The minimum and maximum precedences define the precedence range that the pipe will handle. If a packet arrives with an already allocated precedence below the minimum then its precedence is changed to the minimum. Similarly, if a packet arrives with an already allocated precedence above the maximum, ...

  • Page 410: 10.1.7. Guarantees

    Pipe's configuration is exceeded. Lower priority packets will be buffered and sent when higher priority traffic uses less than the maximum specified for the pipe. The buffering process is sometimes referred to as "throttling back" since it reduces the flow rate. The need for guarantees a problem can...

  • Page 411: 10.1.9. Groups

    Keep the forward chain of both rules as std-out only. Again, to simplify this example, we concentrate only on inbound traffic, which is the direction that is the most likely to be the first one to fill up in client-oriented setups. Set the return chain of the port 22 rule to ssh-in followed by std-i...

  • Page 412

    Computer a is not the same as port 1024 of computer b and individual connections are identifiable. If grouping by network is chosen, the network size should also be specified (this has the same meaning as the netmask). A simple groups scenario if the total bandwidth limit for a pipe is 400 bps and w...

  • Page 413

    Knows what its capacity is and the precedence mechanism is totally dependent on this. Pipe limits for vpn traffic shaping measures the traffic inside vpn tunnels. This is the raw unencrypted data without any protocol overhead so it will be less than the actual vpn traffic. Vpn protocols such as ipse...

  • Page 414

    Consumed by parties outside of administrator control but sharing the same connection. Troubleshooting for a better understanding of what is happening in a live setup, the console command: gw-world:/> pipe -u can be used to display a list of currently active users in each pipe. 10.1.11. A summary of ...

  • Page 415

    The reason for using 2 different pipes in this case, is that these are easier to match to the physical link capacity. This is especially true with asynchronous links such as adsl. First, two pipes called in-pipe and out-pipe need to be created with the following parameters: pipe name min prec def pr...

  • Page 416

    • priority 0 - web plus remaining from other levels to implement this scheme, we can use the in-pipe and out-pipe. We first enter the pipe limits for each pipe. These limits correspond to the list above and are: • priority 6 - 500 • priority 4 - 250 • priority 2 - 1000 now create the pipe rules: rul...

  • Page 417

    The pipe chaining can be used as a solution to the problem of vpn overhead. A limit which allows for this overhead is placed on the vpn tunnel traffic and non-vpn traffic is inserted into a pipe that matches the speed of the physical link. To do this we first create separate pipes for the outgoing t...

  • Page 418

    If sat is being used, for example with a web server or ftp server, that traffic also needs to be forced into pipes or it will escape traffic shaping and ruin the planned quality of service. In addition, server traffic is initiated from the outside so the order of pipes needs to be reversed: the forw...

  • Page 419: 10.2. Idp Traffic Shaping

    10.2. Idp traffic shaping 10.2.1. Overview the idp traffic shaping feature is traffic shaping that is performed based on information coming from the netdefendos intrusion detection and prevention (idp) subsystem (for more information on idp see section 6.5, “intrusion detection and prevention”). The...

  • Page 420: 10.2.3. Processing Flow

    Afterwards when other connections will be opened and subject to traffic shaping. Connections opened after the time window has expired will no longer be subject to traffic shaping. A time window value of 0 means that only traffic flowing over the initial triggering connection will be subject to traff...

  • Page 421: 10.2.5. A P2P Scenario

    Network range but not host x. This tells netdefendos that host x is not relevant in making a decision about including new non-idp-triggering connections in traffic shaping. It may seem counter-intuitive that client b is also included in the network range but this is done on the assumption that clien...

  • Page 422

    Idp traffic shaping has a special cli command associated with it called idppipes and this can examine and manipulate the hosts which are currently subject to traffic shaping. To display all hosts being traffic shaped by idp traffic shaping, the command would be: gw-world:/> idppipes -show host kbps ...

  • Page 423: 10.2.8. Logging

    If the administrator wants to guarantee a bandwidth level, say 10 megabits, for an application then an idp rule can be set up to trigger for that application with the pipe action specifying the bandwidth required. The traffic shaping pipes that are then automatically created get the highest priority...

  • Page 424: 10.3. Threshold Rules

    10.3. Threshold rules 10.3.1. Overview the objective of a threshold rule is to have a means of detecting abnormal connection activity as well as reacting to it. An example of a cause for such abnormal activity might be an internal host becoming infected with a virus that is making repeated connectio...

  • Page 425: 10.3.4. Rule Actions

    • network based - the threshold is applied to all connections matching the rules as a group. 10.3.4. Rule actions when a threshold rule is triggered one of two responses are possible: • audit - leave the connection intact but log the event. • protect - drop the triggering connection. Logging would b...

  • Page 426: 10.4.1. Overview

    10.4. Server load balancing 10.4.1. Overview the server load balancing (slb) feature in netdefendos is a powerful tool that can improve the following aspects of network applications: • performance • scalability • reliability • ease of administration the primary benefit of slb is to allow the network...

  • Page 427

    The additional benefits of slb besides from improving performance and scalability, slb provides a number of other benefits: • slb increases the reliability of network applications by actively monitoring the servers sharing the load. Slb can detect when a server fails or becomes congested and will no...

  • Page 428

    To the same host. Network stickiness this mode is similar to ip stickiness except that by using a subnet mask, a range of hosts in a subnet can be specified. 10.4.4. The distribution algorithm there are several ways to determine how a load is shared across a server farm. Netdefendos slb supports the...

  • Page 429

    When the round robin algorithm is used, the first arriving requests r1 and r2 from client 1 are both assigned to one sever, say server 1, according to stickiness. The next request r3 from client 2 is then routed to server 2. When r4 from client 3 arrives, server 1 gets back its turn again and will b...

  • Page 430: 10.4.6. Slb_Sat Rules

    10.4.5. Server health monitoring slb uses server health monitoring to continuously check the condition of the servers in an slb configuration. Slb can monitor different osi layers to check the condition of each server. Regardless of the algorithms used, if a server is deemed to have failed, slb will...

  • Page 431

    Rule name rule type src interface src network dest interface dest network web_slb_alw allow any all-nets core ip_ext note that the destination interface is specified as core, meaning netdefendos itself deals with this. The key advantage of having a separate allow rule is that the webservers can log ...

  • Page 432

    1. Go to rules > ip rule sets > main > add > ip rule 2. Enter: • name: web_slb_nat • action: nat • service: http • source interface: lan • source network: lannet • destination interface: core • destination network: ip_ext 3. Click ok e. Specify an allow ip rule for the external clients: 1. Go to rul...

  • Page 433

    10.4.6. Slb_sat rules chapter 10. Traffic management 433.

  • Page 434: 11.1. Overview

    Chapter 11. High availability this chapter describes the high availability fault-tolerance feature in netdefend firewalls. • overview, page 434 • ha mechanisms, page 436 • ha setup, page 439 • ha issues, page 443 • ha advanced settings, page 444 11.1. Overview ha clusters netdefendos high availabili...

  • Page 435

    The heartbeat mechanism is discussed below in more depth in section 11.2, “ha mechanisms”. Cluster management an ha cluster of two netdefend firewalls is managed as a single unit with a unique cluster name which appears in the management interface as a single logical netdefend firewall. Administrati...

  • Page 436: 11.2. Ha Mechanisms

    11.2. Ha mechanisms this section discusses im more depth the mechanisms netdefendos uses to implement the high availability feature. Basic principles d-link ha provides a redundant, state-synchronized hardware configuration. The state of the active unit, such as the connection table and other vital ...

  • Page 437

    Failover time the time for failover is typically about one second which means that clients may experience a failover as a slight burst of packet loss. In the case of tcp, the failover time is well within the range of normal retransmit timeouts so tcp will retransmit the lost packets within a very sh...

  • Page 438

    Will lose their synchronization with each other. In other words, the inactive unit will no longer have a correct copy of the state of the active unit. A failover will not occur in this situation since the inactive unit will realize that synchronization has been lost. Failure of the sync interface re...

  • Page 439: 11.3. Ha Setup

    11.3. Ha setup this section provides a step-by-step guide for setting up an ha cluster. 11.3.1. Ha hardware setup the steps for the setup of hardware in an ha cluster are as follows: 1. Start with two physically similar netdefend firewalls. Both may be newly purchased or an existing unit may have a ...

  • Page 440

    Typical ha cluster network connections the illustration below shows the arrangement of typical ha cluster connections in a network. All interfaces on the master unit would normally also have corresponding interfaces on the slave unit and these would be connected to the same networks. This is achieve...

  • Page 441

    2. Go to system > high availability. 3. Check the enable high availability checkbox. 4. Set the cluster id. This must be unique for each cluster. 5. Choose the sync interface. 6. Select the node type to be master. 7. Go to objects > address book and create an ip4 ha address object for each interface...

  • Page 442

    Number on the right is the maximum number of connections allowed by the license. The following points are also relevant to cluster setup: • if this is not the first cluster in a network then the cluster id must be changed for the cluster so that it is unique (the default value is 0). The cluster id ...

  • Page 443: 11.4. Ha Issues

    11.4. Ha issues the following points should be kept in mind when managing and configuring an ha cluster. All cluster interfaces need ip addresses all interfaces on both ha cluster units should have a valid private ip4 address object assigned to them. The predefined ip object local host could be assi...

  • Page 444

    11.5. Ha advanced settings the following netdefendos advanced settings are available for high availability: sync buffer size how much sync data, in kbytes, to buffer while waiting for acknowledgments from the cluster peer. Default: 1024 sync packet max burst the maximum number of state sync packets ...

  • Page 445

    11.5. Ha advanced settings chapter 11. High availability 445.

  • Page 446: Chapter 12. Zonedefense

    Chapter 12. Zonedefense this chapter describes the d-link zonedefense feature. • overview, page 446 • zonedefense switches, page 447 • zonedefense operation, page 448 12.1. Overview zonedefense controls switches zonedefense allows a netdefend firewall to control locally attached switches. It can be ...

  • Page 447: 12.2. Zonedefense Switches

    12.2. Zonedefense switches switch information regarding every switch that is to be controlled by the firewall has to be manually specified in the firewall configuration. The information needed in order to control a switch includes: • the ip address of the management interface of the switch • the swi...

  • Page 448: 12.3.1. Snmp

    12.3. Zonedefense operation 12.3.1. Snmp simple network management protocol (snmp) is an application layer protocol for complex network management. Snmp allows the managers and managed devices in a network to communicate with each other. Snmp managers a typical managing device, such as a netdefend f...

  • Page 449

    As a complement to threshold rules, it is also possible to manually define hosts and networks that are to be statically blocked or excluded. Manually blocked hosts and networks can be blocked by default or based on a schedule. It is also possible to specify which protocols and protocol port numbers ...

  • Page 450: 12.3.5. Limitations

    2. For addresses choose the object name of the firewall's interface address 192.168.1.1 from the available list and put it into the selected list. 3. Click ok configure an http threshold of 10 connections/second: 1. Go to traffic management > threshold rules > add > threshold rule 2. For the thresho...

  • Page 451

    Of latency time to implement blocking once the rule is triggered. Some models can activate blocking in less than a second while some models may require a minute or more. A second difference is the maximum number of rules supported by different switches. Some switches support a maximum of 50 rules wh...

  • Page 452

    12.3.5. Limitations chapter 12. Zonedefense 452.

  • Page 453: 13.1. Ip Level Settings

    Chapter 13. Advanced settings this chapter describes the configurable advanced settings for netdefendos. The settings are divided up into the following categories: note: activating changes after any advanced setting is changed, the new netdefendos configuration must be deployed in order for the new ...

  • Page 454

    Block 0.0.0.0 as source address. Default: drop block 0 net block 0.* as source addresses. Default: droplog block 127 net block 127.* as source addresses. Default: droplog block multicast src block multicast both source addresses (224.0.0.0 - 255.255.255.255). Default: droplog ttl min the minimum ttl...

  • Page 455

    Securemoteudp compatibility allow ip data to contain eight bytes more than the udp total length field specifies. Checkpoint securemote violates nat-t drafts. Default: disabled ip option sizes verifies the size of "ip options". These options are small blocks of information that may be added to the en...

  • Page 456

    Ip reserved flag indicates what netdefendos will do if there is data in the "reserved" fields of ip headers. In normal circumstances, these fields should read 0. Used by os fingerprinting. Default: droplog strip dontfragment strip the don't fragment flag for packets equal to or smaller than the size...

  • Page 457: 13.2. Tcp Level Settings

    13.2. Tcp level settings tcp option sizes verifies the size of tcp options. This function acts in the same way as ipoptionsizes described above. Default: validatelogbad tcp mss min determines the minimum permissible size of the tcp mss. Packets containing maximum segment sizes below this limit are h...

  • Page 458

    Tcp auto clamping automatically clamp tcp mss according to mtu of involved interfaces, in addition to tcpmssmax. Default: enabled tcp zero unused ack determines whether netdefendos should set the ack sequence number field in tcp packets to zero if it is not used. Some operating systems reveal sequen...

  • Page 459

    Initially intended to be used in negotiating for the use of better checksums in tcp. However, these are not understood by any today's standard systems. As netdefendos cannot understand checksum algorithms other than the standard algorithm, these options can never be accepted. The altchkreq option is...

  • Page 460

    Tcp syn/fin the tcp fin flag together with syn; normally invalid (strip=strip fin). Default: droplog tcp fin/urg specifies how netdefendos will deal with tcp packets with both fin (finish, close connection) and urg flags turned on. This should normally never occur, as you do not usually attempt to c...

  • Page 461

    Tcp sequence number validation is only possible on connections tracked by the state-engine (not on packets forwarded using a fwdfast rule). Possible values are: ignore - do not validate. Means that sequence number validation is completely turned off. Validatesilent - validate and pass on. Validatelo...

  • Page 462: 13.3. Icmp Level Settings

    13.3. Icmp level settings icmp sends per sec limit specifies the maximum number of icmp messages netdefendos may generate per second. This includes ping replies, destination unreachable messages and also tcp rst packets. In other words, this setting limits how many rejects per second may be generate...

  • Page 463: 13.4. State Settings

    13.4. State settings connection replace allows new additions to the netdefendos connection list to replace the oldest connections if there is no available space. Default: replacelog log open fails in some instances where the rules section determines that a packet should be allowed through, the state...

  • Page 464

    Default: log log connection usage this generates a log message for every packet that passes through a connection that is set up in the netdefendos state-engine. Traffic whose destination is the netdefend firewall itself, for example netdefendos management traffic, is not subject to this setting. The...

  • Page 465

    13.5. Connection timeout settings the settings in this section specify how long a connection can remain idle, that is to say with no data being sent through it, before it is automatically closed. Please note that each connection has two timeout values: one for each direction. A connection is closed ...

  • Page 466

    Other idle lifetime specifies in seconds how long connections using an unknown protocol can remain idle before it is closed. Default: 130 13.5. Connection timeout settings chapter 13. Advanced settings 466.

  • Page 467

    13.6. Length limit settings this section contains information about the size limits imposed on the protocols directly under ip level, such as tcp, udp and icmp. The values specified here concern the ip data contained in packets. In the case of ethernet, a single packet can contain up to 1480 bytes o...

  • Page 468

    Specifies in bytes the maximum size of an ah packet. Ah, authentication header, is used by ipsec where only authentication is applied. This value should be set at the size of the largest packet allowed to pass through the vpn connections, regardless of its original protocol, plus approx. 50 bytes. D...

  • Page 469

    13.7. Fragmentation settings ip is able to transport up to 65536 bytes of data. However, most media, such as ethernet, cannot carry such huge packets. To compensate, the ip stack fragments the data to be sent into separate packets, each one given their own ip header and information that will help th...

  • Page 470

    Default: check8 – compare 8 random locations, a total of 32 bytes failed fragment reassembly reassemblies may fail due to one of the following causes: • some of the fragments did not arrive within the time stipulated by the reasstimeout or reasstimelimit settings. This may mean that one or more frag...

  • Page 471

    • nolog - no logging is carried out under normal circumstances. • logsuspect - logs duplicated fragments if the reassembly procedure has been affected by "suspect" fragments. • logall - always logs duplicated fragments. Default: logsuspect fragmented icmp other than icmp echo (ping), icmp messages s...

  • Page 472

    Reassembly illegal limit once a whole packet has been marked as illegal, netdefendos is able to retain this in memory for this number of seconds in order to prevent further fragments of that packet from arriving. Default: 60 13.7. Fragmentation settings chapter 13. Advanced settings 472.

  • Page 473

    13.8. Local fragment reassembly settings max concurrent maximum number of concurrent local reassemblies. Default: 256 max size maximum size of a locally reassembled packet. Default: 10000 large buffers number of large ( over 2k) local reassembly buffers (of the above size). Default: 32 13.8. Local f...

  • Page 474

    13.9. Miscellaneous settings udp source port 0 how to treat udp packets with source port 0. Default: droplog port 0 how to treat tcp/udp packets with destination port 0 and tcp packets with source port 0. Default: droplog watchdog time number of non-responsive seconds before watchdog is triggered (0...

  • Page 475

    13.9. Miscellaneous settings chapter 13. Advanced settings 475.

  • Page 476: Updates

    Appendix a. Subscribing to security updates overview the netdefendos anti-virus (av) module, the intrusion detection and prevention (idp) module and the dynamic web content filtering module all function using external d-link databases which contain details of the latest viruses, security threats and...

  • Page 477

    An anti-virus update can similarly be initiated with the command: gw-world:/> updatecenter -update antivirus querying update status to get the status of idp updates use the command: gw-world:/> updatecenter -status idp to get the status of av updates: gw-world:/> updatecenter -status antivirus query...

  • Page 478

    Appendix b. Idp signature groups for idp scanning, the following signature groups are available for selection. These groups are available only for the d-link advanced idp service. There is a version of each group under the three types of ids, ips and policy. For further information see section 6.5, ...

  • Page 479

    Group name intrusion type ftp_formatstring format string attack ftp_general ftp protocol and implementation ftp_login login attacks ftp_overflow ftp buffer overflow game_bomberclone bomberclone game game_general generic game servers/clients game_unreal unreal game server http_apache apache httpd htt...

  • Page 480

    Group name intrusion type pop3_dos denial of service for pop pop3_general post office protocol v3 pop3_login-attacks password guessing and related login attack pop3_overflow pop3 server overflow pop3_request-errors request error portmapper_general portmapper print_general lp printing server: lpr lpd...

  • Page 481

    Group name intrusion type tftp_operation operation attack tftp_overflow tftp buffer overflow attack tftp_reply tftp reply attack tftp_request tftp request attack trojan_general trojan udp_general general udp udp_popup pop-up window for ms windows upnp_general upnp version_cvs cvs version_svn subvers...

  • Page 482

    Appendix c. Verified mime filetypes some netdefendos application layer gateways (algs) have the optional ability to verify that the contents of a downloaded file matches the type that the filetype in the filename indicates. The filetypes for which mime verification can be done are listed in this app...

  • Page 483

    Filetype extension application cpl windows control panel extension file dbm database file dcx graphics multipage pcx bitmap file deb debian linux package file djvu djvu file dll windows dynamic link library file dpa dpa archive data dvi tex device independent document eet eet archive egg allegro dat...

  • Page 484

    Filetype extension application mpv mpeg-1 video file microsoft files microsoft office files, and other microsoft files msa atari msa archive data niff, nif navy interchange file format bitmap noa nancy video codec nsf nes sound file obj, o windows object file, linux object file ocx object linking an...

  • Page 485

    Filetype extension application tfm tex font metric data tiff, tif tagged image format file tnef transport neutral encapsulation format torrent bittorrent metainfo file ttf truetype font txw yamaha tx wave audio files ufa ufa archive data vcf vcard file viv vivoactive player streaming video file wav ...

  • Page 486

    Appendix d. The osi framework overview the open systems interconnection model defines a framework for inter-computer communications. It categorizes different protocols for a great variety of network applications into seven smaller, more manageable layers. The model describes how data from an applica...

  • Page 487

    Appendix e. D-link worldwide offices below is a complete list of d-link worldwide sales offices. Please check your own country area's local website for further details regarding support of d-link products as well as contact details for local support. Australia 1 giffnock avenue, north ryde, nsw 2113...

  • Page 488

    Italy via nino bonnet n. 6/b, 20154 – milano, italy. Tel: 39-02-2900-0676, fax: 39-02-2900-1723. Website: www.Dlink.It latinamerica isidora goyeechea 2934, ofcina 702, las condes, santiago – chile. Tel: 56-2-232-3185, fax: 56-2-232-0923. Website: www.Dlink.Cl luxemburg rue des colonies 11, b-1000 br...

  • Page 489: Alphabetical Index

    Alphabetical index a access rules, 204 accounting, 58 interim messages, 60 limitations with nat, 61 messages, 58 system shutdowns, 61 address book, 75 ethernet addresses in, 77 folders, 79 ip addresses in, 75 address groups, 78 address translation, 297 admin account, 27 changing password for, 36 mul...

  • Page 490

    Block 127 net setting, 454 blocking applications with idp, 278 block multicast src setting, 454 boot menu (see console boot menu) bootp, 198 bpdu relaying, 187 broadcast enet sender setting, 189 c cam size setting, 188 cam to l3 cache dest learning setting, 188 ca servers access, 392 client access, ...

  • Page 491

    Duplicated fragment data setting, 469 duplicate fragments setting, 470 dynamic balancing (in pipes), 411 dynamic cam size setting, 188 dynamic dns, 128 dynamic l3c size setting, 188 dynamic max connections setting, 464 dynamic routing policy, 162 dyndns service, 128 e enable sensors setting, 63 end ...

  • Page 492

    Ike crl validity time setting, 380 ike max ca path setting, 380 ike send crls setting, 380 ike send initial contact setting, 380 ikesnoop vpn troubleshooting, 372, 396 illegal fragments setting, 469 initial silence (ha) setting, 444 insertion attack prevention, 281 interface alias (snmp) setting, 67...

  • Page 493

    Max radius contexts setting, 62 max reassembly time limit setting, 471 max sessions services parameter, 83 max size (reassembly) setting, 473 max skip length setting, 468 max tcp length setting, 467 max time drift setting, 126 max transactions (dhcp) setting, 199 max udp length setting, 467 memlog, ...

  • Page 494

    Dynamic, 157 local ip address, 134 metric for default routes, 138 metrics, 132, 158 monitoring, 140 principles, 132 routes added at startup, 138 static, 132 the all-nets route, 138 s sa (see security association) safestream, 274 sat, 306 all-to-1 mapping, 312 ip rules, 112 multiple address translati...

  • Page 495

    Tcp syn/urg setting, 459 tcp syn idle lifetime setting, 465 tcp urg setting, 460 tcp zero unused ack setting, 458 tcp zero unused urg setting, 458 teriary time server setting, 126 tftp alg, 217 threshold rules, 424, 448 in zonedefense, 448 time synchronization, 122 time sync server type setting, 126...