Remote access to a self hosted Nancy web service

If you’ve only ever run Nancy through Visual Studio or IIS, you will likely have never run into this problem. But if you try to run Nancy under a non-Administrator account–for example, self hosting Nancy in a Windows service running under Network Service–you’ll get a nasty little surprise:

System.Net.HttpListenerException (0x80004005): Access is denied
   at System.Net.HttpListener.AddAllPrefixes()
   at System.Net.HttpListener.Start()

Problem:

Windows does not allow non-Administrator accounts to run HTTP listeners on arbitrary ports. In this case, port 4567.

nancyHost = new Nancy.Hosting.Self.NancyHost(new Uri("http://localhost:4567"));
nancyHost.Start();

Solution:

You will need to open up the port used by Nancy.

netsh http add urlacl url=http://+:4567/ user="NT AUTHORITY\Network Service"

Try your program again and it should now work.

Reference: Stack Overflow