MessageBox.Show("被监控的客户端IP地址不允许空", "确信正确", MessageBoxButtons.OK );

                return;

            }

            Program.order_string = "LOGOUT";

            rev_thread.send_monitor_to_client(comboBox1.Text, textBox1.Text);

        }   

4.2 客户端接收线程部分程序代码

  using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;//用于处理文本的

using System.Threading;

using System.Drawing;

using System.IO;//为TCP通信增加的

using System.Net;//为TCP通信增加的

using System.Net.Sockets;//为TCP通信增加的

using System.Runtime.InteropServices;//供引用API使用

using System.Diagnostics;//关闭指定进程用

namespace Client

{

    public class UdpThread

    {

        //API的引用，主要用于对客户机的控制

        [StructLayout(LayoutKind.Sequential, Pack = 1)]

        internal struct TokPriv1Luid

        {

            public int Count;

            public long Luid;

            public int Attr;

        }

        [DllImport("user32.dll")]//API函数锁定键盘及鼠标

        private static extern void BlockInput(bool Block);

        [DllImport("kernel32.dll", ExactSpelling = true)]

        internal static extern IntPtr GetCurrentProcess();

        [DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]

        internal static extern bool OpenProcessToken(IntPtr h, int acc, ref IntPtr phtok);