试探端口的方法：

public void portAc(object portNoObj)
{
    int portNo = (int)portNoObj;
    TcpClient TcpScan = new TcpClient();
    try
    {
        // Try to connect

        TcpScan.Connect(ipAdres, portNo);

        if (!TcpScan.Connected) return;
        // If there's no exception, we can say the port is open

        log += "Port " + portNo + " open\r\n";

        //NOTE: We may include more finger tips to here

        switch (portNo)
        {
            case 80: http = true; break;
        }

        try
        {
            DataRow dr = dt.NewRow();
            dr[0] = "http://www.portsdb.org/bin/portsdb.cgi?portnumber=" + 
                     portNo + "&protocol=ANY&String=";
            dt.Rows.Add(dr);
        } // Ends Try

        catch (Exception Err)
        {
            throw Err;
        }
    }
    catch
    {
        // An exception occured, thus the port is probably closed

    }
}