CODEWITHSUNDEEP
c#.netuwploopback
DotNetRussell
DotNetRussell

Reputation: 9857

Loopback Isolation Removal not working For UWP App

So I setup a simple StreamSocketListener in my UWP 

    StreamSocketListener listener = new StreamSocketListener();
    public async void StartServer()
    {
        await listener.BindServiceNameAsync("8282");
        listener.ConnectionReceived +=  async (s, a) =>
        {
            using (var output = a.Socket.OutputStream)
            {
                using (var response = output.AsStreamForWrite())
                {
                    var html = Encoding.UTF8.GetBytes(
                    $"<html><head><title>Background Message</title></head><body>Hello from the background process!<br/></body></html>");
                    using (var bodyStream = new MemoryStream(html))
                    {
                        var header = $"HTTP/1.1 200 OK\r\nContent-Length: {bodyStream.Length}\r\nConnection: close\r\n\r\n";
                        var headerArray = Encoding.UTF8.GetBytes(header);
                        await response.WriteAsync(headerArray,
                                                  0, headerArray.Length);
                        await bodyStream.CopyToAsync(response);
                        await response.FlushAsync();
                    }
                }
            }
        };
    }

Then, I added this to my app manifest with the package family name I got out of the gui for the package manifest. 

  <Extensions>
    <uap4:Extension Category="windows.loopbackAccessRules">
      <uap4:LoopbackAccessRules>
        <uap4:Rule Direction="out" PackageFamilyName="<my package fam name>" />
        <uap4:Rule Direction="in" PackageFamilyName="<my package fam name>" />
      </uap4:LoopbackAccessRules>
    </uap4:Extension>
  </Extensions>

I went in and setup the proper capabilities

<Capability Name="privateNetworkClientServer"/>
<Capability Name="internetClientServer"/>
<uap3:Capability Name="remoteSystem"/>
<Capability Name="internetClient"/>

Finally, I enabled loopback with checknetisolation as show in this post UWP Enable local network loopback

However, my webserver is only accessable from other devices on my network. It won't connect if I

I tried connecting from Chrome, Firefox, FireFox with a Proxy to it, and curl

I ran netstat -ano | FIND "8282" and I can see the port is open

  TCP    0.0.0.0:8282           0.0.0.0:0              LISTENING       5920
  TCP    [::]:8282              [::]:0                 LISTENING       5920

I also tried running checknetisolation debug -n=<my package fam name> but there was no real info in the output 

Summary Report

Network Capabilities Status
----------------------------------------------------------------------
    InternetClient                Not Used and Insecure
    InternetClientServer          Not Used and Insecure
    PrivateNetworkClientServer    Not Used and Insecure


Detailed Traffic Report
----------------------------------------------------------------------

    InternetClient                Not Used and Insecure

 ------------------------------------------------------------------


    InternetClientServer          Not Used and Insecure

 ------------------------------------------------------------------


    PrivateNetworkClientServer    Not Used and Insecure

 ------------------------------------------------------------------

OK.

I'm at a loss of where to go now

Upvotes: 2

Views: 1098

Answers (1)

Barry Wang
Barry Wang

Reputation: 1469

You are right. And to make this more clear, please see this doc for enable loopback part. Where you will see the following comments:

"Further, a Windows Runtime app can use an IP loopback only as the target address for a client network request. So a Windows Runtime app that uses a DatagramSocket or StreamSocketListener to listen on an IP loopback address is prevented from receiving any incoming packets."

Upvotes: 1

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