Accessing SharePoint/IIS sites in Firefox for Mac

I was reminded of this little quirk today when Heather pinged me as she was setting up her new Mac:

If you’re getting a 401 Unauthorized access error when trying to get to a SharePoint site on Firefox for Mac, it’s because you have to change a config setting. From Stack Overflow:

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.

To Enable NTLMv1 in Firefox

  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.

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