D-Link DFL-260E User Manual page 367

7.2. NAT
gw-world:/main> cc
The NATAction option could be left out since the default value is to use the interface address. The alternative is to
specify UseSenderAddress and use the NATSenderAddress option to specify the IP address to use. The sender
address will also need to be explicitly ARP published on the interface.
Web Interface
1. Go to: Rules > IP Rules > Add > IPRule
2. Specify a suitable name for the rule, for example NAT_HTTP
3. Now enter:
• Action: NAT
• Service: http
• Source Interface: lan
• Source Network: lannet
• Destination Interface: wan
• Destination Network: all-nets
4. Under the NAT tab, make sure that the Use Interface Address option is selected
5. Click OK
Logging can optionally be enabled for this rule so that a log message is generated each time it is triggered.
Protocols Handled by NAT
Dynamic address translation is able to deal with the TCP, UDP and ICMP protocols with a good
level of functionality since the algorithm knows which values can be adjusted to become unique in
the three protocols. For other IP level protocols, unique connections are identified by their sender
addresses, destination addresses and protocol numbers.
This means that:
• An internal machine can communicate with several external servers using the same IP protocol.
• An internal machine can communicate with several external servers using different IP protocols.
• Several internal machines can communicate with different external servers using the same IP
protocol.
• Several internal machines can communicate with the same server using different IP protocols.
• Several internal machines can not communicate with the same external server using the same IP
protocol.
Note: Restrictions only apply to IP level protocols
These restrictions apply only to IP level protocols other than TCP, UDP and ICMP,
such as OSPF and L2TP. They do not apply to the protocols transported by TCP, UDP
and ICMP such as telnet, FTP, HTTP and SMTP.
NetDefendOS can alter port number information in the TCP and UDP headers to
make each connection unique, even though such connections have had their sender
addresses translated to the same IP.
367
Chapter 7. Address Translation