檢查遠端 IP 是否存在(Ping 的使用)

using System.Net.NetworkInformation;
 
Ping ping = new Ping();
PingReply reply = ping.Send("IP 位置");
if (reply.Status == IPStatus.Success)
{
    MessageBox.Show(string.Format("IP：{0}連接成功！", reply.Address));
}
else
{
    MessageBox.Show(string.Format("IP：{0}連接失敗！", reply.Address));
}

public partial class Form8 : Form
{
    private string host;
    private Ping ping;
    private byte[] buffer = Encoding.ASCII.GetBytes("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
    private int timeout = 5000;// Wait 5秒
    private bool runThread;
    Thread pingThread;
 
    public Form8()
    {
        InitializeComponent();
        CheckForIllegalCrossThreadCalls = false;
    }
 
    private void btnPing_Click(object sender, EventArgs e)
    {
        this.richTextBox1.Clear();
        host = this.tbHost.Text;
        if (host.Length == 0)
            throw new Exception("請輸入主機名稱 or IP位置");
        ping = new Ping();      
 
        //同步模式
        /*PingReply reply = ping.Send(host, timeout, buffer);
        display(reply);*/
 
        //異步模式, 不可直接用在form, 必須獨立 thread
        runThread = true;
        pingThread = new Thread(this.sendPing);
        pingThread.Start();
    }
    private void sendPing()
    {
        AutoResetEvent waiter = new AutoResetEvent(false);
        ping.PingCompleted += new PingCompletedEventHandler(pingCompletedCallback);
        PingOptions options = new PingOptions(64, true);
        while (runThread)
        {
            ping.SendAsync(host, timeout, buffer, options, waiter);
            waiter.WaitOne();
            Thread.Sleep(1000);//當前線程 sleep
        }
    }
    public void pingCompletedCallback(object sender, PingCompletedEventArgs e)
    {
        if (e.Cancelled)
        {
            addLine("退出Ping");
            ((AutoResetEvent)e.UserState).Set();//繼續主線程
        }
        if (e.Error != null)
        {
            addLine("Ping 失敗");
            addLine(e.Error.ToString());
            ((AutoResetEvent)e.UserState).Set();
        }
        PingReply reply = e.Reply;
        display(reply);
        ((AutoResetEvent)e.UserState).Set();
    }
    public void display(PingReply reply)
    {
        if (reply == null) return;
        addLine("ping 狀態:" + reply.Status);
        if (reply.Status == IPStatus.Success)
        {
            addLine("位置:" + reply.Address.ToString());
            addLine("時間:" + reply.RoundtripTime);
            addLine("TTL:" + reply.Options.Ttl);
            addLine("不許可數據損壞:" + reply.Options.DontFragment);
            addLine("緩衝區:" + reply.Buffer.Length);
        }
    }
    private void addLine(string data, bool newLine = true)
    {
        richTextBox1.AppendText(data + Environment.NewLine);
    }
 
    private void Form8_FormClosing(object sender, FormClosingEventArgs e)
    {
        pingThread.Abort();
    }
 
    private void btnStop_Click(object sender, EventArgs e)
    {
        runThread = false;
        // Use the Join method to block the current thread until the object's thread terminates.
        pingThread.Join();
    }
}