根據IP地址獲得主機名稱
// .NET 1.1 ~
System.Net.IPHostEntry host = System.Net.Dns.GetHostByAddress("192.168.0.1"); // [msdn]
Console.WriteLine(host.HostName);

// .NET 2.0 ~
System.Net.IPHostEntry host = System.Net.Dns.GetHostEntry("192.168.0.1"); // [msdn]
Console.WriteLine(host.HostName);


取得本機IP
static void Main(string[] args)
{
  // 顯示主機名
  string hostname = Dns.GetHostName();
  Console.WriteLine("hostname = {0}", hostname);

  // 顯示每個IP地址
  IPHostEntry hostent = Dns.GetHostByName(hostname); // 主機信息
  IPAddress[] addrs = hostent.AddressList; // IP地址數組
  foreach ( IPAddress ip in hostent.AddressList )
  {
    Console.WriteLine("Address: {0}", ip);
  } // foreach
}
　

VB, VBA

using System; using System.Net; using System.Net.Sockets; using System.Text; public class NetworkHelper { public static string GetLastError() { return _LastError; } private static string _LastError = string.Empty; public static bool Ping(string hostnameOrIp) { Socket host = null; try { // 對hostname的處理 IPHostEntry hostInfo; try { hostInfo = Dns.GetHostByName(hostnameOrIp); } // try catch(Exception) { _LastError = string.Format("Unknown host {0}", hostnameOrIp); return false; } // catch IPEndPoint iep= new IPEndPoint(hostInfo.AddressList[0], 0); EndPoint ep = (EndPoint)iep; byte[] data = new byte[1024]; int recv; host = new Socket(AddressFamily.InterNetwork, SocketType.Raw,ProtocolType.Icmp); ICMP packet = new ICMP(); packet.Type = 0x08; packet.Code = 0x00; packet.Checksum = 0; Buffer.BlockCopy(BitConverter.GetBytes((short)1), 0, packet.Message, 0, 2); Buffer.BlockCopy(BitConverter.GetBytes((short)1), 0, packet.Message, 2, 2); data = Encoding.ASCII.GetBytes("test packet"); Buffer.BlockCopy(data, 0, packet.Message, 4, data.Length); packet.MessageSize = data.Length + 4; int packetsize = packet.MessageSize + 4; UInt16 chcksum = packet.getChecksum(); packet.Checksum = chcksum; host.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 3000); host.SendTo(packet.getBytes(), packetsize, SocketFlags.None, iep); try { data = new byte[1024]; recv = host.ReceiveFrom(data, ref ep); return true; } // try catch (SocketException) { _LastError = "No response from remote host"; return false; } // catch // // 結果 // ICMP response = new ICMP(data, recv); // Console.WriteLine("response from: {0}", ep.ToString()); // Console.WriteLine(" Type {0}", response.Type); // Console.WriteLine(" Code: {0}", response.Code); // int Identifier = BitConverter.ToInt16(response.Message, 0); // int Sequence = BitConverter.ToInt16(response.Message, 2); // Console.WriteLine(" Identifier: {0}", Identifier); // Console.WriteLine(" Sequence: {0}", Sequence); // string stringData = Encoding.ASCII.GetString(response.Message, 4, response.MessageSize - 4); // Console.WriteLine(" data: {0}", stringData); } // try catch { _LastError = string.Format("Unknown host {0}", hostnameOrIp); return false; } // catch finally { if ( host!=null ) host.Close(); } // finally } class ICMP { public byte Type; public byte Code; public UInt16 Checksum; public int MessageSize; public byte[] Message = new byte[1024]; public ICMP() {} public ICMP(byte[] data, int size) { Type = data[20]; Code = data[21]; Checksum = BitConverter.ToUInt16(data, 22); MessageSize = size - 24; Buffer.BlockCopy(data, 24, Message, 0, MessageSize); } public byte[] getBytes() { byte[] data = new byte[MessageSize + 9]; Buffer.BlockCopy(BitConverter.GetBytes(Type), 0, data, 0, 1); Buffer.BlockCopy(BitConverter.GetBytes(Code), 0, data, 1, 1); Buffer.BlockCopy(BitConverter.GetBytes(Checksum), 0, data, 2, 2); Buffer.BlockCopy(Message, 0, data, 4, MessageSize); return data; } public UInt16 getChecksum() { UInt32 chcksm = 0; byte[] data = getBytes(); int packetsize = MessageSize + 8; int index = 0; while ( index < packetsize) { chcksm += Convert.ToUInt32(BitConverter.ToUInt16(data, index)); index += 2; } chcksm = (chcksm >> 16) + (chcksm & 0xffff); chcksm += (chcksm >> 16); return (UInt16)(~chcksm); } } // class ICMP } // class NetworkHelper

使用範例：
public class MainProc
{
 public static void Main(string[] argv)
 {
  // 測試
  bool ret = NetworkHelper.Ping(argv[0]);
  Console.WriteLine("Ping [{0}] = {1}", argv[0], ret);
 }
} 　

注意事項：

• .NET 2.0 以上有Ping Class可以直接使用。[msdn]

參考資料：

• http://www.java2s.com/Code/CSharp/Network/SimplePing.htm