As part of Firefox 30′s release, Mozilla made a change to disable support for NT LAN Manager version 1 (NTLMv1) network authentication. This change affects sites using Microsoft’s SharePoint or IIS services. The Windows version of Firefox 30 should switch to using NTLMv2 authentication automatically, but NTLMv2 is not supported by Firefox on non-Windows platforms.
The result for non-Windows platforms is that access may be blocked when Firefox 30 users try to access those kinds of sites.
Mozilla has provided a workaround to non-Windows users of Firefox, in the form of a setting that can be toggled to allow NTLMv1 authentication. This workaround should allow Mac and Linux users to continue using NTLMv1 authentication, which will allow access again to SharePoint-based or IIS-backed web applications. For more details, see below the jump.
Enabling NTLMv1 in Firefox 30
1. Open Firefox
2. In the address bar, enter the following:
about:config
3. If prompted, click on the I’ll be careful, I promise! button.
4. Search for the following:
network.negotiate-auth.allow-insecure-ntlm-v1
5. Once the network.negotiate-auth.allow-insecure-ntlm-v1 setting is located, double-click on the setting. That should change the entry in the Value column from false to true.
6. Once the network.negotiate-auth.allow-insecure-ntlm-v1 setting has been set to true, close the Firefox browser window.
7. Open a new browser window and attempt to access the SharePoint-based or IIS-backed site. You should now be able to log in.
