//自动获取ip 
rip是个下拉列表 
public void GetIp()
{
      try
      {
         string strHostName = Dns.GetHostName();  //得到本机的主机名 
         IPHostEntry ipEntry = Dns.GetHostByName(strHostName); //取得本机IP 
         string strAddr = ipEntry.AddressList[0].ToString();
         rip.Text = strAddr; 
         rip.Items.Clear();
         for (int i = 0; i < 10; i++)
         {
                strAddr = ipEntry.AddressList[i].ToString();
                rip.Items.Add(strAddr);
          }


      }
      catch{}
}