Find the next TCP port in .NET

I want to create a new net.tcp://localhost:x/Service endpoint for a WCF service call, with a dynamically assigned new open TCP port.

I know that TcpClient will assign a new client side port when I open a connection to a given server.

Is there a simple way to find the next open TCP port in .NET?

I need the actual number, so that I can build the string above. 0 does not work, since I need to pass that string to another process, so that I can call back on that new channel.

Solution 1:

Here is what I was looking for:

static int FreeTcpPort()
{
  TcpListener l = new TcpListener(IPAddress.Loopback, 0);
  l.Start();
  int port = ((IPEndPoint)l.LocalEndpoint).Port;
  l.Stop();
  return port;
}

Solution 2:

Use a port number of 0. The TCP stack will allocate the next free one.

Solution 3:

It's a solution comparable to the accepted answer of TheSeeker. Though I think it's more readable:

using System;
using System.Net;
using System.Net.Sockets;

    private static readonly IPEndPoint DefaultLoopbackEndpoint = new IPEndPoint(IPAddress.Loopback, port: 0);

    public static int GetAvailablePort()
    {
        using (var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
        {
            socket.Bind(DefaultLoopbackEndpoint);
            return ((IPEndPoint)socket.LocalEndPoint).Port;
        }
    }