> Source: [sk33650](https://support.checkpoint.com/results/sk/sk33650)

# sk33650 - Static NAT failing and Automatic Proxy ARP not working following upgrade

| Property | Value |
|----------|-------|
| Solution ID | sk33650 |
| Date Created | 2007-10-04 |
| Last Modified | 2017-11-27 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |

## Symptoms

- * Static NAT is failing. Automatic Proxy ARP is not working following an upgrade.  

* Output of '`fw ctl arp`' command is empty.  

* SmartDashboard - Policy menu - Global Properties - NAT - both '`Automatic ARP configuration`' and '`Merge manual proxy ARP configuration`' boxes are checked.

## Cause

The names used for the Security Gateway's interfaces in the "`Topology`" settings are different than the interface names used on the Security Gateway machine (as see in the output of '`ifconfig -a`' command).

## Solution

Names of the interfaces in Security Gateway object (in "Topology") must match the Names of the interfaces on Security Gateway machine.

Follow these steps:

1. Open Security Gateway object - go to "`Topology`" pane - change the names of the interfaces to match the names of the interfaces on Security Gateway machine.

2. Install the policy.

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