> Source: [sk123116](https://support.checkpoint.com/results/sk/sk123116)

# sk123116 - DHCP relay traffic drop after policy installation

| Property | Value |
|----------|-------|
| Solution ID | sk123116 |
| Date Created | 2018-02-23 |
| Last Modified | 2018-11-12 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |
| OS | Gaia |

## Symptoms

- * DHCP relay traffic drop after policy installation.
* Running kernel debug (fw ctl debug -m fw + drop) is showing the following log:  
  `dropped by fw_handle_old_conn_recovery Reason: UDP packet that belongs to an old session;`
* Rebooting upstream switch temporarily resolves the issue until the next policy installation.

## Cause

The drops are caused by a policy installation and the mechanism associated with matching old and new connections. When a policy is installed, all the existing connections are marked with OLD flag. After this happens, client to server packets that arrive are being re-matched in rulebase and OLD flag is removed. But, if server to client packet arrives on an OLD connection it is dropped by the Security Gateway.

## Solution

This solution requires authentication. Please log in to view the full solution.

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