C# socket programming

using System; // For Console, Int32, ArgumentException, Environment
using System.Net; // For IPAddress
using System.Net.Sockets; // For TcpListener, TcpClient

class TcpEchoServer {

private const int BUFSIZE = 32; // Size of receive buffer

static void Main(string[] args) {

if (args.Length > 1) // Test for correct # of args
throw new ArgumentException("Parameters: [<port>]");

int servPort = (args.Length == 1) ? Int32.Parse(args[0]): 7;

TcpListener listener = null;

try {
    // Create a TCPListener to accept client connections
listener = new TcpListener(IPAddress.Any, servPort);
listener.Start();
} catch (SocketException se) {
  
Console.WriteLine(se.ErrorCode + ": " + se.Message);
Environment.Exit(se.ErrorCode);
}

byte[] rcvBuffer = new byte[BUFSIZE]; // Receive buffer
int bytesRcvd; // Received byte count
for (;;) { // Run forever, accepting and servicing connections
TcpClient client = null;
NetworkStream netStream = null;

 try {
 client = listener.AcceptTcpClient(); // Get client connection
 netStream = client.GetStream();
 Console.Write("Handling client - ");

 // Receive until client closes connection, indicated by 0 return value
 int totalBytesEchoed = 0;
 while ((bytesRcvd = netStream.Read(rcvBuffer, 0, rcvBuffer.Length)) > 0) {
 netStream.Write(rcvBuffer, 0, bytesRcvd);
 totalBytesEchoed += bytesRcvd;
 }
 Console.WriteLine("echoed {0} bytes.", totalBytesEchoed);

 // Close the stream and socket. We are done with this client!
 netStream.Close();
 client.Close();

 } catch (Exception e) {
 Console.WriteLine(e.Message);
 netStream.Close();
 }
 }
 }
 }</port>