How to configure NAT on NSSP 13700 ?

07/13/2021 0 1889

DESCRIPTION:

This article describes how to access an internal device or server behind the SonicWall firewall remotely from outside the network. This process is also known as opening ports, PATing, NAT or Port Forwarding.

RESOLUTION:

NOTE: During the initial release, NSSP 13700 is only available in global mode. In a later release, SonicOSX with Policy mode will be available for selection.

By default, SonicWall has an implicit rule that denies all inbound traffic to something on the LAN Zone or the Custom Zone having the devices, servers behind the firewall. This is to protect internal devices from malicious access, however, it is often necessary to open up certain parts of a network, such as Servers, to the outside world.

To accomplish this the SonicWall needs a Firewall Access Rule to allow the traffic from the public Internet to the internal network as well as a Network Address Translation (NAT) Policy to direct the traffic to the correct device.

Manually opening port forwarding to allow traffic from the Internet to a Server behind the SonicWall using SonicOS involves the following steps:

1. Creating the necessary Address Objects and Service Object for the custom port access.
2. Creating the appropriate NAT Policies which can include Inbound, Outbound, and Loopback
3. Creating the necessary Firewall Access Rules
   
   These steps will also allow you to enable Port Address Translation with or without altering the IP Addresses involved.

The following walk-through details allowing Terminal Service (RDP) Traffic from the Internet to a server on the LAN. Once the configuration is complete, Internet Users can access the Server via the Public IP Address of SonicWall's WAN.

Creating the necessary Address Objects

1. Login to the SonicWall GUI.
2. Click Object in the top navigation menu.
3. Click Match Objects | Addresses.
4. Click Add and create two Address Objects for the Server's Public IP and the Server's Private IP.
5. Click Save to add the Address Object to SonicWall's Address Object Table.

Creating the necessary Service Object

1. Click Object in the top navigation menu
2. Click Match Objects | Services.
3. Click the Add button and create the necessary Service Objects for the Ports required.
4. Ensure that you know the correct Protocol for the Service Object (TCP, UDP, etc.). If you're unsure of which Protocol is in use, perform a Packet Capture.
5. Click Save to add the Service Object to SonicWall's Service Object Table.

Creating the appropriate NAT Policies which can include Inbound, Outbound, and Loopback

A NAT Policy will allow SonicOS to translate incoming Packets destined for a Public IP Address to a Private IP Address, and/or a specific Port to another specific Port. Every Packet contains information about the Source and Destination IP Addresses and Ports and with a NAT Policy SonicOS can examine Packets and rewrite those Addresses and Ports for incoming and outgoing traffic.

1. Click Policy in the top navigation menu.
2. Click Rules and Policies| NAT Rules.
3. Click the Add button at the bottom of the page and a pop-up window will appear.   

 For the Inbound NAT policy, select the fields as below on the Original and translated tabs. Leave all fields on the Advanced/Actions tab as default. Click on Add to add the NAT Policy to the SonicWall NAT Policy Table.  Specifying the Interfaces is a best practice.

For the Outbound NAT policy, select the fields as below on the Original and translated tabs. Leave all fields on the Advanced/Actions tab as default. Click on Add to add the NAT Policy to the SonicWall NAT Policy Table.

Loopback NAT Policy
A Loopback NAT Policy is required when Users on the Local LAN/WLAN need to access an internal Server via its Public IP/Public DNS Name. This Policy will "Loopback" the Users request for access as coming from the Public IP of the WAN and then translate down to the Private IP of the Server. Without a Loopback NAT Policy internal Users will be forced to use the Private IP of the Server to access it which will typically create problems with DNS.
If you wish to access this server from other internal zones using the Public IP address consider creating a Loopback NAT Policy.    

 Creating the necessary Firewall Access Rules

1. Click Policy in the top navigation menu.
2. Click Rules and Policies | Access Rules.
3. Select the View Type as Matrix and select your WAN to Appropriate Zone Access Rule. (This will be the Zone the Private IP of the Server resides on.)
4. Click the Add button at the bottom of the screen and in the pop-up window create the required Access Rule by configuring the fields as shown below in the Source/Destination tab. Leave all other tabs on default.
5. Click Add when finished.