1、在Windows下用CMD netstat命令可以获得当前进程监听端口号的信息，如netstat -ano可以看到IP、port、状态和监听的PID。
那么可以执行CMD这个进程得到监听的端口号信息，C#代码如下：
//进程id
int pid = ProcInfo.ProcessID;
//存放进程使用的端口号链表
List ports = new List();
Process pro = new Process();
pro.StartInfo.FileName = "cmd.exe";
pro.StartInfo.UseShellExecute = false;
pro.StartInfo.RedirectStandardInput = true;
pro.StartInfo.RedirectStandardOutput = true;
pro.StartInfo.RedirectStandardError = true;
pro.StartInfo.CreateNoWindow = true;
pro.Start();
pro.StandardInput.WriteLine("netstat -ano");
pro.StandardInput.WriteLine("exit");
Regex reg = new Regex("\s+", RegexOptions.Compiled);
string line = null;
ports.Clear();
while ((line = pro.StandardOutput.ReadLine()) != null)
{
line = line.Trim();
if (line.StartsWith("TCP", StringComparison.OrdinalIgnoreCase))
{
line = reg.Replace(line, ",");
string[] arr = line.Split(',');
if (arr[4] == pid.ToString())
{
string soc = arr[1];
int pos = soc.LastIndexOf(':');
int pot = int.Parse(soc.Substring(pos + 1));
ports.Add(pot);
}
}
else if (line.StartsWith("UDP", StringComparison.OrdinalIgnoreCase))
{
line = reg.Replace(line, ",");
string[] arr = line.Split(',');
if (arr[3] == pid.ToString())
{
string soc = arr[1];
int pos = soc.LastIndexOf(':');
int pot = int.Parse(soc.Substring(pos + 1));
ports.Add(pot);
}
}
}
pro.Close();