看起来PID是4（系统），因为实际的侦听套接字位于名为http的服务下。
我查看了iisexpresstray.exe用来提供所有正在运行的IISExpress应用程序列表的内容，谢天谢地，它是托管的.NET代码（都在iisexpresstray.dll中），很容易反编译。
它似乎至少有三种不同的方法来获取进程的端口号：
1.从命令行参数阅读/port（我们知道不可靠）
1.运行netsh http show servicestate view=requestq并解析输出
1.调用Microsoft.Web.RuntimeStatusClient.GetWorkerProcess(pid)并解析站点URL
不幸的是，iisexpresstray.dll中的大多数有用的东西，如IisExpressHelper类，都声明为internal（尽管我认为有工具可以生成 Package 器或复制程序集并公布所有内容）。
我选择使用Microsoft.Web.dll。它在我的GAC中，但由于某种原因没有出现在可作为Visual Studio中的引用添加的程序集列表中，所以我只是从GAC中复制了该文件。一旦我有了Microsoft.Web.dll，就只需要使用以下代码：

using (var runtimeStatusClient = new RuntimeStatusClient())
    {
      var workerProcess = runtimeStatusClient.GetWorkerProcess(process.Id);
      // Apparently an IISExpress process can run multiple sites/applications?
      var apps = workerProcess.RegisteredUrlsInfo.Select(r => r.Split('|')).Select(u => new { SiteName = u[0], PhysicalPath = u[1], Url = u[2] });
      // If we just assume one app
      return new Uri(apps.FirstOrDefault().Url).Port;
     }

您也可以呼叫RuntimeClient.GetAllWorkerProcesses，只撷取实际的背景工作行程序。
我还研究了RegisteredUrlsInfo（在Microsoft.Web.dll中），发现它使用两个COM接口，

1. IRsca2_Core（F90F62AB-EE00-4E4F-8EA6-3805B6B25CDD）
2. IRsca2_WorkerProcess（B1341209-7F09-4ECD-AE5F-3EE40D921870）
   最后，我读到了Microsoft.Web.Administration的一个版本，它显然能够读取IISExpress应用程序信息，但是信息非常缺乏，而且我在系统上找到的那个版本甚至不允许我在没有管理员权限的情况下示例化ServerManager。

下面是调用netsh.exe的C#实现，如@makhdumi的答案中所建议的：

用法：

static public bool TryGetCurrentProcessRegisteredHttpPort(out List<int> ports, out Exception ex)
{
    NetshInvoker netsh = new NetshInvoker();
    return netsh.TryGetHttpPortUseByProcessId(Process.GetCurrentProcess().Id, out ports, out ex);
}

实作：

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;

namespace YourCompanyName.Server.ServerCommon.Utility
{
    /// <summary>
    /// Invoke netsh.exe and extract information from its output.
    /// Source: @crokusek, https://stackoverflow.com/questions/32196188
    ///         @GETah, https://stackoverflow.com/a/8274758/538763
    /// </summary>
    public class NetshInvoker
    {
        const string NetshHttpShowServiceStateViewRequestqArgs = "http show servicestate view=requestq";

        public NetshInvoker()
        {
        }

        /// <summary>
        /// Call netsh.exe to determine the http port number used by a given windowsPid (e.g. an IIS Express process)
        /// </summary>
        /// <param name="windowsPid">For example an IIS Express process</param>
        /// <param name="port"></param>
        /// <param name="ex"></param>
        /// <returns></returns>
        public bool TryGetHttpPortUseByProcessId(Int32 windowsPid, out List<Int32> ports, out Exception ex)
        {
            ports = null;

            try
            {
                if (!TryQueryProcessIdRegisteredUrls(out Dictionary<Int32, List<string>> pidToUrlMap, out ex))
                    return false;

                if (!pidToUrlMap.TryGetValue(windowsPid, out List<string> urls))
                {
                    throw new Exception(String.Format("Unable to locate windowsPid {0} in '{1}' output.",
                        windowsPid, "netsh " + NetshHttpShowServiceStateViewRequestqArgs));
                }

                if (!urls.Any())
                {
                    throw new Exception(String.Format("WindowsPid {0} did not reference any URLs in '{1}' output.",
                        windowsPid, "netsh " + NetshHttpShowServiceStateViewRequestqArgs));
                }

                ports = urls
                    .Select(u => new Uri(u).Port)
                    .ToList();

                return true;
            }
            catch (Exception ex_)
            {
                ex = ex_;
                return false;
            }
        }

        private bool TryQueryProcessIdRegisteredUrls(out Dictionary<Int32, List<string>> pidToUrlMap, out Exception ex)
        {
            if (!TryExecNetsh(NetshHttpShowServiceStateViewRequestqArgs, out string output, out ex))
            {
                pidToUrlMap = null;
                return false;
            }

            bool gotRequestQueueName = false;
            bool gotPidStart = false;
            int currentPid = 0;
            bool gotUrlStart = false;

            pidToUrlMap = new Dictionary<int, List<string>>();

            foreach (string line in output.Split('\n').Select(s => s.Trim()))
            {
                if (!gotRequestQueueName)
                {
                    gotRequestQueueName = line.StartsWith("Request queue name:");
                }
                else if (!gotPidStart)
                {
                    gotPidStart = line.StartsWith("Process IDs:");
                }
                else if (currentPid == 0)
                {
                    Int32.TryParse(line, out currentPid);   // just get the first Pid, ignore others.
                }
                else if (!gotUrlStart)
                {
                    gotUrlStart = line.StartsWith("Registered URLs:");
                }
                else if (line.ToLowerInvariant().StartsWith("http"))
                {
                    if (!pidToUrlMap.TryGetValue(currentPid, out List<string> urls))
                        pidToUrlMap[currentPid] = urls = new List<string>();

                    urls.Add(line);
                }
                else // reset
                {
                    gotRequestQueueName = false;
                    gotPidStart = false;
                    currentPid = 0;
                    gotUrlStart = false;
                }
            }
            return true;
        }

        private bool TryExecNetsh(string args, out string output, out Exception exception)
        {
            output = null;
            exception = null;

            try
            {
                // From @GETah, https://stackoverflow.com/a/8274758/538763

                Process p = new Process();
                p.StartInfo.FileName = "netsh.exe";
                p.StartInfo.Arguments = args;
                p.StartInfo.UseShellExecute = false;
                p.StartInfo.RedirectStandardOutput = true;
                p.Start();

                output = p.StandardOutput.ReadToEnd();
                return true;
            }
            catch (Exception ex)
            {
                exception = ex;
                return false;
            }
        }
    }
}

在我的情况下，我只是在任务管理器中输出“命令行”列，它变得很明显，其中IISExpress是：

您可以运行以下命令来获取可执行文件及其PID的信息

netstat -a -n -o -b | find "iisexpress.exe"