Central NAT table
The central NAT table enables you to define, and control with more granularity, the address translation performed by the FortiGate unit. With the NAT table, you can define the rules which dictate the source address or address group and which IP pool the destination address uses.
While similar in functionality to IP pools, where a single address is translated to an alternate address from a range of IP addresses, with IP pools there is no control over the translated port. When using the IP pool for source NAT, you can define a fixed port to guarantee the source port number is unchanged. If no fix port is defined, the port translation is randomly chosen by the FortiGate unit. With the central NAT table, you have full control over both the IP address and port translation.
The FortiGate unit reads the NAT rules in a top-down methodology, until it hits a matching rule for the incoming address. This enables you to create multiple NAT policies that dictate which IP pool is used based on the source address. The NAT policies can be rearranged within the policy list as well. NAT policies are applied to network traffic after a security policy.
The Central NAT tab allows you to create, edit, delete, and clone central NAT entries. The following information is displayed for these entries: NAT ID, Status, Original Address, Original Source Port, Translated Address, Translated Port, and Last Modified (admin and date and time that the entry was last modified). Select the checkbox in the Status column to enable or disable the central NAT entry.
| Select Display Options in the Policy & Objects tab, and toggle the Central NAT switch to display this option in the Policy Package tab bar. |
To create a new central NAT entry:
1. Select the ADOM from the drop-down list in the toolbar.
2. Select the policy package where you are creating the new interface policy from the tree menu.
3. Select Central NAT in the policy toolbar.
4. Select Create New from the toolbar.
The New NAT page opens.
5. Configure the following settings:
Source Address | Select the source address from the drop-down list. You can select to create a new address or address group in the Source Address dialog box. |
Translated Address | Select the translated address from the drop-down list. You can select to create a new IP Pool in the Translated Address dialog box. |
Original Source Port | Enter the original source port range. |
Translated Port | Enter the translated port range. |
6. Select OK to save the setting.
