Which Protocols Can Nat Handle; Adding A Nat Policy - D-Link NetDefend DFL-210 User Manual

7.1.1. Which Protocols can NAT
handle?
1. The sender, e.g. 192.168.1.5, sends a packet from a dynamically assigned port, for instance,
port 1038, to a server, e.g. 195.55.66.77 port 80.
192.168.1.5:1038 => 195.55.66.77:80
2. In this example, the Use Interface Address option is used, and we will use 195.11.22.33 as the
interface address. In addition, the source port is changed to a free port on the D-Link Firewall,
usually one above 32768. In this example, we will use port 32789. The packet is then sent to its
destination.
195.11.22.33:32789 => 195.55.66.77:80
3. The recipient server then processes the packet and sends its response.
195.55.66.77:80 => 195.11.22.33:32789
4. NetDefendOS receives the packet and compares it to its list of open connections. Once it finds
the connection in question, it restores the original address and forwards the packet.
195.55.66.77:80 => 192.168.1.5:1038
5. The original sender receives the response.
Example 7.1. Adding a NAT Policy
To add a policy that will perform address translation for all HTTP traffic originating from the internal network, fol-
low the steps outlined below:
CLI
gw-world:/> add IPRule Action=NAT Service=http SourceInterface=lan
Web Interface
1. Go to Rules > IP Rules > Add > IPRule
2. Specify a suitable name for the rule, for instance NAT_HTTP.
3. Now enter:
• Action: NAT
• Service: http
• Source Interface: lan
• Source Network: lannet
• Destination Interface: any
• Destination Network: all-nets
4. Under the NAT tab, make sure that the Use Interface Address option is selected.
5. Click OK.

7.1.1. Which Protocols can NAT handle?

Dynamic address translation is able to handle the TCP, UDP and ICMP protocols with a good level
of functionality since the algorithm knows of values that can be adjusted to become unique in the
three protocols. For other IP level protocols, unique connections are identified by their sender ad-
SourceNetwork=lannet DestinationInterface=any
DestinationNetwork=all-nets Name=NAT_HTTP NATAction=UseInterfaceAddress
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Chapter 7. Address Translation