Thread: Setting ToS/Diffserv byte?

I found some sample code on setting the ToS byte of an IP packet that you are sending out in C#, but can't seem to get it to work. What I have is very simple:

Code:

public static void Main(string[] args)
        {
            Console.WriteLine("Testing DSCP packet marking.Wireshark should already be running!\n");

            UdpClient cli = new UdpClient();
            //TcpClient cli = new TcpClient();
            cli.Client.SetSocketOption(SocketOptionLevel.IP,
                                       SocketOptionName.TypeOfService, 136);

            byte[] buf = new byte[16];

            //I fill buff here            
            
            cli.Connect("192.168.4.100", 10100);
            cli.Send(buf, buf.Length);
            /*NetworkStream mystream = cli.GetStream();
            if (mystream != null)
            {
                mystream.Write(buf, 0, buf.Length);
            }
            if(cli.Connected)
                cli.Close();*/
        }

As you can see, I've tried this with both TCP and UDP. But when I view the traffic that gets sent out in wireshark, the diffserve byte is always 0. I can see that the payload is filled with what I set buf too, so I know I'm looking at my packet. Am I missing something?

Yes. According to Wireshark, it's still 0.

I didn't realize Ubuntu could run .NET code. But I'm sending from Windows 7 with no luck.