新建net.cs文件，编写客户端程序，创建Socket后，客户端通过connect连接服务器，然后向服务器发送hello unity.发送后等待服务器回应，并把服务器回应的字符串显示出来。

using UnityEngine;
using System.Collections;
using System.Net;
using System.Net.Sockets;
using UnityEngine.UI;

public class net : MonoBehaviour
{
//与服务端的套接字
Socket socket;
//服务端的IP和端口
public InputField hostInput;
public InputField portInput;
//文本框
public Text recvText;
public Text clientText;
//接收缓冲区
const int BUFFER_SIZE = 1024;
byte[] readBuff = new byte[BUFFER_SIZE];

public void Connetion()
{
//Socket
socket = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
//Connect
string host = hostInput.text;
int port = int.Parse(portInput.text);
socket.Connect(host, port);
clientText.text = "客户端地址 " + socket.LocalEndPoint.ToString();
//Send
string str = "Hello Unity!";
byte[] bytes = System.Text.Encoding.Default.GetBytes(str);
socket.Send(bytes);
//Recv
int count = socket.Receive(readBuff);
str = System.Text.Encoding.UTF8.GetString(readBuff, 0, count);
recvText.text = str;
//Close
socket.Close();
}
}

socket客户端程序