TW-H6W1IR ISDN Remote Router
Configuration and Management 79
In the Outgoing Data Packet above, the Source IP address is the IP
address that is translated by NAT. The Destination IP Address is the
IP address of a computer outside the private network, on the Internet
for example. And the Data portion of the packet is the information
payload borne by the packet, for instance a request to view a web
page.
The router logs the changes made to the IP header in its NAT table.
The NAT table enables the router to send replies back to the local
computer as shown below.
In the Inbound Data Packet above, the Destination IP Address is the
IP address that is translated by NAT. The Source IP Address is the IP
address of a computer outside the private network. And the Data
portion of the packet is the information payload borne by the packet,
for example, the contents of a web page.
The actual information in the NAT table depends whether the router is
implementing NAT or NAPT.
It is also of interest to note that this translation process provides a level
of security to your network found in a firewall. If you examine the
outbound and inbound packets above closely, you can see that the
computer outside of the network that is receiving the packet and
sending the response only knows about the global IP address used by
the router, and actually sends the response to that address. The outside
