Listen for ICMP packets in C#

Question

I have a SIP application that needs to send UDP packets to set up the SIP calls. SIP has a timeout mechanism to cope with delivery failures. An additional thing I would like to be able to do is detect whether a UDP socket is closed in order having to wait the 32s retransmit interval SIP uses.

The cases I am referring to are when an attempt to send to a UDP socket results in an ICMP Destination Unreachable packet being generated by the remote host. If I attempt to send a UDP packet to a host that's up but that the port is not listening I can see the ICMP message arriving back with a packet tracer but the question is how do I get access to that from my C# code?

I'm playing around with raw sockets but as yet have not been able to get the ICMP packets to be received by my program. The sample below never receives a packet even though ICMP messages are arriving on my PC.

Socket icmpListener = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);
icmpListener.Bind(new IPEndPoint(IPAddress.Any, 0));

byte[] buffer = new byte[4096];
EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
int bytesRead = icmpListener.ReceiveFrom(buffer, ref remoteEndPoint);
logger.Debug("ICMPListener received " + bytesRead + " from " + remoteEndPoint.ToString());

Below is a wireshark trace showing the ICMP responses coming into my PC from an attempt to send a UDP packet from 10.0.0.100 (my PC) to 10.0.0.138 (my router) on a port I know it's not listening on. My problem is how to make use of those ICMP packets to realise the UDP send has failed rather than just waiting for the application to timeout after an arbitrary period?

Answer 1

Nearly 3 years later and I stumbled across http://www.codeproject.com/Articles/17031/A-Network-Sniffer-in-C which gave me enough of a hint to help me find a solution to receiving ICMP packets on Windows 7 (don't know about Vista, which the original question was about but I suspect this solution would work).

The two key points are that the socket has to be bound to a single specific IP address rather than IPAddress.Any and the IOControl call which sets the SIO_RCVALL flag.

Socket icmpListener = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);
icmpListener.Bind(new IPEndPoint(IPAddress.Parse("10.1.1.2"), 0));
icmpListener.IOControl(IOControlCode.ReceiveAll, new byte[] { 1, 0, 0, 0 }, new byte[] { 1, 0, 0, 0 });

byte[] buffer = new byte[4096];
EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
int bytesRead = icmpListener.ReceiveFrom(buffer, ref remoteEndPoint);
Console.WriteLine("ICMPListener received " + bytesRead + " from " + remoteEndPoint);
Console.ReadLine();

I also had to set a firewall rule to allow ICMP Port Unreachable packets to be received.

netsh advfirewall firewall add rule name="All ICMP v4" dir=in action=allow protocol=icmpv4:any,any

Answer 2

UPDATE: I think I'm going crazy.... That piece of code that you posted is also working for me...

The following piece of code works fine for me(xp sp3):

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

namespace icmp_capture
{
    class Program
    {
        static void Main(string[] args)
        {            
            IPEndPoint ipMyEndPoint = new IPEndPoint(IPAddress.Any, 0);
            EndPoint myEndPoint = (ipMyEndPoint);
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);            
            socket.Bind(myEndPoint);
            while (true)
            {

                /*                
                //SEND SOME BS (you will get a nice infinite loop if you uncomment this)
                var udpClient = new UdpClient("192.168.2.199", 666);   //**host must exist if it's in the same subnet (if not routed)**              
                Byte[] messagebyte = Encoding.Default.GetBytes("hi".ToCharArray());                
                int s = udpClient.Send(messagebyte, messagebyte.Length);
                */

                Byte[] ReceiveBuffer = new Byte[256];
                var nBytes = socket.ReceiveFrom(ReceiveBuffer, 256, 0, ref myEndPoint);
                if (ReceiveBuffer[20] == 3)// ICMP type = Delivery failed
                {
                    Console.WriteLine("Delivery failed");
                    Console.WriteLine("Returned by: " + myEndPoint.ToString());
                    Console.WriteLine("Destination: " + ReceiveBuffer[44] + "." + ReceiveBuffer[45] + "." + ReceiveBuffer[46] + "." + ReceiveBuffer[47]);
                    Console.WriteLine("---------------");
                }
                else {
                    Console.WriteLine("Some (not delivery failed) ICMP packet ignored");
                }
            }

        }
    }
}