This article applies to PRTG Network Monitor 13 or later

Using NTML Authentication with Unix-based Servers

There are often problems with Windows NT LAN Manager (NTML) authentications when using Apache or other specific Linux servers, because NTML is a proprietary Windows protocol (see Microsoft’s TechNet article Network security: LAN Manager authentication level). In addition, several Unix-based webservers only support NTML v1, but as of Windows 7 only NTML v2 is activated by default.

However, as a workaround, you can reactivate NTML v1 in order to use this authentication protocol on your (Linux) webservers.

Important notice: Disabling Windows’ default security setting is not recommended. Do it on your own responsibility.

Reactivating NTML v1 as a Workaround for Specific Webservers

In order to enable NTML v1, follow the steps below as pointed out in the article NTML authentication with Drupal+Apache+Linux on “In just five minutes…”.

Steps to Go

1. Open the Control Panel of Windows 7.
2. Choose Administrative Tools.
3. Click on Local Security Policy.
4. Choose Local Policies | Security Options.
5. Search for the entry Network Security: LAN Manager Authentication Level.
6. Change this level to Send LM & NTML responses.

Now Internet Explorer will be able to use NTML v1.

For Firefox, you have to add your application URL to the trusted URI list:

1. Open Firefox.
2. Call about:config via the address bar and accept the warning message.
3. Search for the entry network.automatic-ntml-auth.trusted-uris.
4. Double-click it (or right-click > Edit) and enter the URL of your application.
5. Click on OK.

After you have accomplished these steps, you might have to set up your webserver accordingly for NTML v1 authentication. For details, please see NTML authentication with Drupal+Apache+Linux.