string hostName = Dns.GetHostName();
var addrs = Dns.GetHostAddresses(hostName);
bool hasIP = false;
for (int i = 0; i < addrs.Length; i++)
{
    IPAddress addr = addrs[i];
    if (addr.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
    {
        si.DataIP = addr.ToString();
        hasIP = true;
        break;
    }
}

Creating a socket is easy here is how:

using System.Net.Sockets;

//...

// Creating a connection
Socket client;
client = new Socket( AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp );
client.Connect(hostName, port);
client.Blocking = false; // This needs to be done after Connect or it will error out.

Here’s how to write data to the socket

// Writing information to the socket
byte[] buffer = ASCIIEncoding.ASCII.GetBytes(messageText);
foreach (byte c in buffer)
{
	SocketError err = SocketError.WouldBlock;
	// need to try again if the socket would have blocked
	while ( err == SocketError.WouldBlock )
	{
		// this version of Send must be used or an exception would be thrown, which I feel is a pain
		// to deal with -- this way you can see handle the error appropriately.
		client.Send(buffer, 0, 1, SocketFlags.None, out err );
	}

	if ( err != SocketError.Success )
	{
		// handle error
		break;
	}
}

And now code to read from a non-blocking socket

// Reading from the socket
// this loop keeps going until there is a socket error or a '0' byte is read which
// in this example marks the end of the message
System.Text.StringBuilder message = new System.Text.StringBuilder();
while ( true )
{
	byte c = 0;
	int bytesRead;
	SocketError err;
	// read a character.
	bytesRead = client.Receive(buffer, 0, 1, SocketFlags.None, out err );
	// checking what happened
	if ( SocketError.Success == err )
	{
		// read a byte!  Let's process it
		if ( bytesRead > 0 )
		{
			// found a null character -- in this case it makes the end of a message.
			if (c == 0)
			{
				// null terminated message received
				break;
			}
			else
				message.Append((char)c);
			}
		}
	}
	else if ( SocketError.WouldBlock != err )
	{
		break;
	}
}