Form1.cs

 private string GetLocalIP ()
        {
            IPHostEntry host;
            host = Dns.GetHostEntry ( Dns.GetHostName () );
            foreach ( IPAddress ip in host.AddressList )
            {
                if ( ip.AddressFamily.Equals ( AddressFamily.InterNetwork ) ) return ip.ToString ();
            }
            return "127.0.0.1";
        }