> Source: [sk177944](https://support.checkpoint.com/results/sk/sk177944)

# sk177944 - Identity Collector does not connect to AD Domain Controller

| Property | Value |
|----------|-------|
| Solution ID | sk177944 |
| Date Created | 2022-02-16 |
| Last Modified | 2025-05-13 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |
| OS | Windows |

## Symptoms

- * Identity Collector does not connect to a Windows Domain Controller (DC) server that is configured as an Identity Source.

* In the Identity Collector interface \> Identity Source \> in the corresponding Active Directory object, the "Test" shows "`Unable to connect`".

* Traffic capture between the Windows Server with Identity Collector and the Windows Domain Controller shows that the Windows Domain Controller sends a TCP \[RST\] packet to the Identity Collector computer and closes the connection.

## Cause

**There are 3 possible causes of this issue:**   

* The NTLM authentication level of the DC Server is different from the NTLM authentication level of the Windows Server that hosts Identity Collector.
* A Firewall between the Windows Server with Identity Collector and the Windows Domain Controller blocks the required Microsoft DCOM communication.  
  Identity Collector and the DC Server use the DCE/RPC protocol for DCOM communication.  
  This communication uses many different ports, and not only the default port 135.
* The user's password contains the character " (quotation mark).

<br />

## Solution

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

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