> Source: [sk1171](https://support.checkpoint.com/results/sk/sk1171)

# sk1171 - Error message in FireWall-1 Log Viewer comment field: "local interface address spoofing"

| Property | Value |
|----------|-------|
| Solution ID | sk1171 |
| Date Created | 2000-12-28 |
| Last Modified | 2014-05-01 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |

## Symptoms

- Error message in FireWall-1 Log Viewer comment field: "local interface address spoofing"

## Cause

The FireWall will drop any packet it receives with a source IP address that belongs to one of its interfaces. Local interface address spoofing messages may also occur if a packet is received with a source IP address that is on the same subnet as one of the FireWall's interfaces. This happens regardless of whether or not you configure Anti-Spoofing on your interfaces and it cannot be bypassed.

## Solution

Verify that when a packet leaves the FireWall for its destination that it doesn't have to return to FireWall. For instance if FireWall has a route to send a packet to the default gateway, yet the default gateway has a route to send the packet back to FireWall. This packet will then be dropped since the packet has a source IP of an interface on FireWall.

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