> Source: [sk183500](https://support.checkpoint.com/results/sk/sk183500)

# sk183500 - Security Gateway drops MSRPC traffic

| Property | Value |
|----------|-------|
| Solution ID | sk183500 |
| Date Created | 2025-06-04 |
| Last Modified | 2025-07-08 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82, R81.20, R81.10 (EOS) |

## Symptoms

- A client initiates a DCE-RPC control connection on Port TCP 135, followed by RPC communication on a random high port.

SmartConsole logs shows that when the client tries to send traffic on the connection two hours later, the service changes from DCE-RPC to MSRPC, and the Security Gateway drops it.

## Cause

* Keepalive packets are expected to traverse the Security Gateway and refresh the kernel table timeouts.
* When the Security Gateway does not receive keepalive packets, the connection entries timeout in *dcerpc_maps* and *dcerpc_maps_multi_match* kernel tables are not refreshed and continue to count down.
* When the connection is resumed, only *dcerpc_maps* and *dcerpc_rmaps* kernel tables entries are refreshed, but the connection entry in the *dcerpc_maps_multi_match* table does not refresh.
* When the high port traffic was dropped and seen as MSRPC in the logs, the PC would start with TCP/135 again within about a minute and it would self-correct.

## Solution

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

---

# Agent Instructions

This content is from the Check Point Support Center (https://support.checkpoint.com), the official knowledge base for Check Point cybersecurity products.

## Navigating This Knowledge Base

- **Complete index**: [llms.txt](https://support.checkpoint.com/llms.txt)
- **All SK articles**: [SecureKnowledge Sitemap](https://support.checkpoint.com/sitemaps/secureknowledge-sitemap-index.xml)
- **SK article URL pattern**: `https://support.checkpoint.com/results/sk/{skId}`
- **Markdown responses**: AI bot User-Agents automatically receive `text/markdown` content