Lancom Systems LCOS 3.50 - Manual (Page 74)

LANCOM Reference Manual LCOS 3.50 ̈ Chapter 7: Routing and WAN connections
74
Routing and
W
A
N
con
n
ections
assume a certain order that differs from the protocol standard. In this case the
SYN/ACK speedup can be deactivated:
7.3 The hiding place—IP masquerading (NAT, PAT)
One of today's most common tasks for routers is connecting the numerous
workstation computers in a LAN to the network of all networks, the Internet.
Everyone should have the potential to access, for example, the WWW from his
workstation and be able to fetch bang up-to-date information for his work.
7.3.1 Simple masquerading
IP masquerading provides a hiding place for every computer while connected
with the Internet. Only the router module of the LANCOM and its IP address
are visible on the Internet. The IP address can be fixed or assigned dynamically
by the provider. The computers in the LAN then use the router as a gateway
so that they themselves cannot be detected. Thereby, the router separates
Internet and Intranet.
How does IP masquerading work?
Masquerading makes use of a characteristic of TCP/IP data transmission,
which is to use port numbers for destination and source as well as the source
and destination addresses. When the router receives a data packet for transfer
it now notes the IP address and the sender's port in an internal table. It then
gives the packet its unique IP address and a new port number, which could be
Configuration tool Menu/table
LANconfig IP router ̈ General ̈ Pass on TCP SYN and ACK packets prefer-
entially
WEBconfig Expert Configuration ̈ Setup ̈ IP-router-module ̈
Routing-method ̈ SYN/ACK-speedup
Terminal/Telnet cd /setup/IP-router-module/routing-
method set SYN/ACK-speedup OFF