Is it possible to use HTTP (NOT HTTPS) over port 443?

I wonder if it is possible to communicate plain HTTP (no SSL) over the TCP port 443?

Trying to change the address of my WCF based server to use the port 443 (but no SSL) fails with this message:

Shunra.Common.Wcf.ShunraServiceHost - O开发者_开发知识库pen failed with exception
System.ServiceModel.AddressAlreadyInUseException: HTTP could not register URL http://+:443/NC/. Another application has already registered this URL with HTTP.SYS. ---> System.Net.HttpListenerException: Failed to listen on prefix 'http://+:443/NC/' because it conflicts with an existing registration on the machine.
   at System.Net.HttpListener.AddAllPrefixes()
   at System.Net.HttpListener.Start()
   at System.ServiceModel.Channels.SharedHttpTransportManager.OnOpen()
   --- End of inner exception stack trace ---
   at System.ServiceModel.Channels.SharedHttpTransportManager.OnOpen()
   at System.ServiceModel.Channels.TransportManager.Open(TransportChannelListener channelListener)
   at System.ServiceModel.Channels.TransportManagerContainer.Open(SelectTransportManagersCallback selectTransportManagerCallback)
   at System.ServiceModel.Channels.TransportChannelListener.OnOpen(TimeSpan timeout)
   at System.ServiceModel.Channels.HttpChannelListener.OnOpen(TimeSpan timeout)
   at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
   at System.ServiceModel.Dispatcher.ChannelDispatcher.OnOpen(TimeSpan timeout)
   at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
   at System.ServiceModel.ServiceHostBase.OnOpen(TimeSpan timeout)
   at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
   at System.ServiceModel.Channels.CommunicationObject.Open()
   at Shunra.Common.Wcf.ShunraServiceHost.Open() in c:\dev\windows\Common\Shunra.Common\Wcf\ShunraServiceHost.cs:line 65

And this is not the matter of HTTP namespace reservation, since the user is an administrator.

So, I am wondering whether there is a special treatment of the port 443 as to only allow HTTPS over it.

Thanks.

Notice that the error message says

Another application has already registered this URL with HTTP.SYS.

So this seems to indicate that another application already uses port 443, and that this is the problem. You can only have several applications listen on the same port if they differ in their host header.