Lantronix ETS Reference Manual - 2.7 Tcp/ip
Concepts
TCP/IP
2-7
Suppose Bob is logged into port 4 on his ETS and the server manager has given port 4 access to groups 1,
7, 13, and 105. Bob, or anyone else using port 4, can only access services that have one of those group
numbers. Suppose Bob wishes to access a modem on a different server. If the server to which the modem
is attached allows access to groups 8, 12, 16, 42, and 105; Bob will be allowed to use the modem because
he and the modem service have group 105 in common.
Note:
See Set/Define Port Authorized Groups on page 12-28 and Set/Define Server
Service Groups on page 12-80 for more information.
Group numbers also are useful to nodes because each node only needs to pay attention to multicasts that
involve its users’ groups. As a result, groups can hide services that would otherwise be visible. The server
manager can also hide services from a set of ports. Setting up and managing services and groups is discussed
in more detail in the Server Configuration chapter, next.
ETS units used in the LAT environment support remote configuration of server ports by VMS hosts. This
feature of the LAT software allows the server to implement VMS commands that change a user’s “terminal
line.” For instance, if user Bob connects to a VMS host and types the command Set Terminal/Speed=2400,
the speed will be changed on the host and the host will ask the ETS to change the “real” terminal line (in
this case, Bob’s serial port on the server). This feature supports changes to parity and flow control as well.
Note:
Remote control can be disabled; see Set/Define Port Remote Configure on page
12-49.
2.7 TCP/IP
2.7.1 IP Addresses
Every TCP/IP node on a network has an IP address, which is unique to that network and an Ethernet
Address, which is unique across all hardware in the world. The IP address provides information needed to
forward packets across multiple networks, if necessary.
The address is of the form n.n.n.n, where each n is a number from zero to 254, as in 192.0.0.1. The exception
is that there cannot be a zero in the last segment of the address.
Note:
The number 255 is strictly reserved for broadcast packets.
A unique IP address must be specified on the ETS before any of the TCP/IP functionality is available. See
your Installation Guide for more information on configuring the IP address.
A DHCP server can be used to temporarily assign a leased IP address to the ETS. See Dynamic Host Control
Protocol (DHCP) on page 12-10 for more information.