> Source: [sk111171](https://support.checkpoint.com/results/sk/sk111171)

# sk111171 - Security Gateway in HTTP/HTTPS Proxy mode sends TCP RST packet in response to TCP SYN packet

| Property | Value |
|----------|-------|
| Solution ID | sk111171 |
| Date Created | 2016-04-28 |
| Last Modified | 2025-05-20 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82, R81.20, R81.10 (EOS), R81 (EOS) |
| OS | Gaia |

## Symptoms

- Security Gateway in HTTP/HTTPS Proxy mode sends TCP RST packet in response to TCP SYN packet.
*Example of TCPdump traffic capture* :  

```

12:05:19.833686 IP IP_of_Client.62628 > IP_of_Proxy_GW.8080: S 1881248280:1881248280(0) win 8192
12:05:19.834011 IP IP_of_Proxy_GW.8080 > IP_of_Client.62628: R 0:0(0) ack 1881248281 win 0
12:05:19.834019 IP IP_of_Proxy_GW.8080 > IP_of_Client.62628: R 0:0(0) ack 1 win 0
```

## Cause

1. Web browser on the client sends the HTTP/HTTPS traffic to the interface of the Security Gateway, whose "Topology" is defined as "External" in Security Gateway object.

2. Choosing an Interface as a proxy that is not the interface connected to the clients.

## Solution

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