Network > NAT Policies

The Network Address Translation (NAT) engine in SonicOS allows users to define granular NAT polices for their incoming and outgoing traffic. By default, the Dell SonicWALL Security Appliance has a preconfigured NAT policy to allow all systems connected to the X0 interface to perform Many-to-One NAT using the IP address of the X1 interface, and a policy to not perform NAT when traffic crosses between the other interfaces. This section explains how to set up the most common NAT policies.

Understanding how to use NAT policies starts with an the construction of an IP packet. Every packet contains addressing information that allows the packet to get to its destination, and for the destination to respond to the original requester. The packet contains (among other things) the requester’s IP address, the protocol information of the requestor, and the destination’s IP address. The NAT Policies engine in SonicOS can inspect the relevant portions of the packet and can dynamically rewrite the information in specified fields for incoming, as well as outgoing traffic.

You can add up to 512 NAT Policies on a Dell SonicWALL Security Appliance running SonicOS, and they can be as granular as you need. It is also possible to create multiple NAT policies for the same object — for instance, you can specify that an internal server use one IP address when accessing Telnet servers, and to use a totally different IP address for all other protocols. Because the NAT engine in SonicOS supports inbound port forwarding, it is possible to hide multiple internal servers off the WAN IP address of the firewall. The more granular the NAT Policy, the more precedence it takes.

Table 34 shows the maximum number of routes and NAT policies allowed for each SonicOS 6.2 network security appliance model.

 

Table 34. Maximum routes and NAT policies allowed per network security appliance model

Model	Routes	NAT Policies
TZ 300	—	512
TZ 400	—	512
TZ 500	—	512
TZ 600	—	512
NSA 2600	—	1024
NSA 3600	—	1024
NSA 4600	—	1024
NSA 5600	—	2048
NSA 6600	1024	2048
SM 9200	1024	2048
SM 9400	1024	2048
SM 9600	1024	2048

Topics:

•	NAT Policies Table

•	NAT Policy Settings

•	NAT Load Balancing Overview

•	Creating NAT Policies

•	Using NAT Load Balancing