3Com OfficeConnect 3C16771, User Manual, Page: 141 / 182

Protecting an Existing Network with the Internet Firewall 25 141
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Purchase an additional IP address.
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Use NAT: It is possible that only some of the PCs will
require their own IP address to be presented to the
Internet. The example “Expanding the number of IP
addresses available using NAT” describes how to make
better use of multiple IP addresses supplied by an ISP,
whilst still allowing Internet access for all the PCs that
require it.
In this example, it is assumed that the address
172.16.54.16
can be freed.
1 Switch off the cable modem and connect the Internet
Firewall 25 ports.
a Connect the WAN port of the Internet Firewall 25 to the
Ethernet port on the cable modem.
b Connect the LAN port to the hub or switch that all the
PCs are connected together through, or directly to one
PC from which you intend to manage the Internet
Firewall 25 (the management station).
If the Internet Firewall 25 is connected directly to one PC,
then this reduces the risk of another user on the network
configuring the Internet Firewall 25 before you have
changed the default password.
2 Assuming that you are managing the Internet Firewall 25
from the PC with address
172.16.54.15
(either by direct
connection, or through a hub/switch), switch on the
Internet Firewall 25 and check the LEDs.
a Wait for the Power LED to stop flashing (approximately
90 seconds).
b Make sure that the orange Alert LED is also out when
the flashing stops. If the Alert LED comes on, or the
Firewall
Power LED keeps flashing, see Chapter 6 for
troubleshooting information.
3 Change the IP address of the management station so that it
is in the same subnet as your Internet Firewall.
a The default IP address of your Internet Firewall is
192.168.1.254.
Thus, select an IP address in the same