 <p>Install your own nuget server behind the firewall/proxy and point to that as your default NuGet server.</p> <p>I've used the free version of <a href="http://inedo.com/proget/overview" rel="nofollow">ProGet</a> in the past as an easy to run a nuget server that also acts as a caching proxy for the main nuget gallery. It also means that if the main nuget server or your internet connection is down you will still have a nuget server that your build can connect to.</p>