CheckPort.cs

 bool inUse = false;

        System.Net.NetworkInformation.IPGlobalProperties ipProperties = System.Net.NetworkInformation.IPGlobalProperties.GetIPGlobalProperties();
        System.Net.IPEndPoint[] ipEndPoints = ipProperties.GetActiveUdpListeners();


        foreach (System.Net.IPEndPoint endPoint in ipEndPoints)
        {
            if (endPoint.Port == port)
            {
                inUse = true;
                break;
            }
        }