> Source: [sk100214](https://support.checkpoint.com/results/sk/sk100214)

# sk100214 - NTLM authentication fails with "401 Unauthorized" when the proxy feature is enabled on Security Gateway

| Property | Value |
|----------|-------|
| Solution ID | sk100214 |
| Date Created | 2014-04-10 |
| Last Modified | 2016-03-14 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |

## Symptoms

- * When trying to connect to a site that requires NTLM authentication from Internet Explorer browser, the authentication pop-up does not appear, and the message "401 Unauthorized" immediately appears instead.

* When using Chrome browser or Firefox browser, the authentication pop-up appears. However, valid credentials will also redirect to "401 Unauthorized" message.

## Cause

Proxy feature does not support NTLM authentication.

## Solution

This feature is not included in the product. If you need it, please submit a [Request for Enhancement](https://www.checkpoint.com/rfe/login.htm).

NTLM authentication for proxy server is also not supported for manual IPS updates.

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