Remote access to a self hosted Nancy web service

07 January 2013 |

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()


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"));


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

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Yoeun Pen

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