Find the next TCP port in .NET
I found the following code from Selenium.WebDriver DLL
Namespace: OpenQA.Selenium.Internal
Class: PortUtility
public static int FindFreePort()
{
int port = 0;
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
IPEndPoint localEP = new IPEndPoint(IPAddress.Any, 0);
socket.Bind(localEP);
localEP = (IPEndPoint)socket.LocalEndPoint;
port = localEP.Port;
}
finally
{
socket.Close();
}
return port;
}
Use a port number of 0. The TCP stack will allocate the next free one.
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;
}
}
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;
}