[转]用C#获取局域网内所有机器

原理其实很简单，在cmd.exe下面ping一下几台机，然后用arp -a命令查看一下，这种方式比开多线程去循环扫描的方式来的简单而有效。
//首先来个循环ping一下那个网段的主机。
//其次用以下的函数去获取所有的局域网内有响应的ip地址列表
public static ArrayList GetAllLocalMachines()
{   
 Process p = new Process();   
 p.StartInfo.FileName = "cmd.exe";   
 p.StartInfo.UseShellExecute = false;   
 p.StartInfo.RedirectStandardInput = true;   
 p.StartInfo.RedirectStandardOutput = true;   
 p.StartInfo.RedirectStandardError = true;   
 p.StartInfo.CreateNoWindow = true;   
 p.Start();   
 p.StandardInput.WriteLine("arp -a");   
 p.StandardInput.WriteLine("exit");   
 ArrayList list = new ArrayList();   
 StreamReader reader = p.StandardOutput;   
 string IPHead = Dns.GetHostByName(Dns.GetHostName()).AddressList[0].ToString().Substring(0, 3);   
 for (string line = reader.ReadLine(); line != null; line = reader.ReadLine())   
 {       
  line = line.Trim();       
  if (line.StartsWith(IPHead) && (line.IndexOf("dynamic") != -1))       
  {           
   string IP = line.Substring(0, 15).Trim();           
   string Mac = line.Substring(line.IndexOf("-") - 2, 0x11).Trim();           
   LocalMachine localMachine = new LocalMachine();           
   localMachine.MachineIP = IP;           
   localMachine.MachineMAC = Mac;           
   localMachine.MachineName = "";           
   list.Add(localMachine);       
  }   
 }   
 return list;
}