> Source: [sk36161](https://support.checkpoint.com/results/sk/sk36161)

# sk36161 - "Unexpected post SYN packet - RST or SYN expected" log in SmartView Tracker

| Property | Value |
|----------|-------|
| Solution ID | sk36161 |
| Date Created | 2008-10-28 |
| Last Modified | 2018-03-15 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |

## Symptoms

- * Packets are dropped with '`Unexpected post SYN packet - RST or SYN expected`' log in SmartView Tracker.

* Packets are dropped with '`Illegal post SYN packet`' log in SmartView Tracker.

## Cause

RFC states that before getting the SYN-ACK, or any other packet from the Server, Client can send only a RST (to close connection), or SYN (retransmission, in case the first SYN did not arrive).

Any packet from the Client other than SYN or RST, is considered as a security violation, because it seems that the Client tries to send packets before the Server has responded to the initial request (SYN).

## Solution

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

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