3Com OfficeConnect 3C16771, User Manual

Page: 118 / 182

118 C
HAPTER
4: C
OMMAND
R
EFERENCE
■
DMZ/WAN
The IP addresses of the DMZ, if appropriate, and WAN
ports are shown. These differ from that of the LAN port
if NAT is enabled. Configure these in the Network
Settings window (see
Figure 16 ). You can specify the
Subnet mask , if it is different from the default.
■
Add Route
Type the destination network of the router in the Dest.
Network box, and the IP address of the router as it
appears on Internet Firewall’s subnet in the Gateway
box. From the Link drop-down list, select the port on
the Internet Firewall,
LAN or WAN , that the router is
connected to. You may have to check the configuration
of the LAN routers in order to find this information.
Click Update to send the configuration data to the Internet
Firewall.
Setting up One-to-One NAT
One-to-One NAT creates a relationship which maps valid
external addresses to internal addresses hidden by NAT.
Machines with an internal address may be accessed at the
corresponding external valid IP address.
To create this relationship between internal and external
addresses, define internal and external address ranges of
equal length. Once you have defined that relationship, the
machine with the first internal address is accessible at the
first IP address in the external address range, the second
machine at the second external IP address, and so on.
Consider a LAN for which the ISP has assigned the IP
addresses range from
209.19.28.16
to
209.19.28.31
,
with
209.19.28.16
used as the NAT Public Address. The
address range of
192.168.1.1
to
192.168.1.255
is used
for the machines on the LAN. Typically, only machines that
have been designated as Public LAN Servers are accessible
from the Internet. However, with One-to-One NAT, the
machines with the internal IP addresses of
192.168.1.2
to
192.168.1.16
are accessible at the corresponding external
IP address, as shown in Table 4 .