Best way to check if a TCP connection is active

Given a list of IP addresses how do I programmatically check if the local machine still has active TCP connections to these IP Addresses? I am using C#.

From stackoverflow

• Call GetExtendedTcpTable and check through the list for your target addresses

• using System.Net.NetworkInformation    
  
  IPGlobalProperties properties = IPGlobalProperties.GetIPGlobalProperties();
  TcpConnectionInformation[] tcpInfoList = properties.GetActiveTcpConnections();
  

  Noldorin : Good solution... I wasn't actually aware there was a simple managed call to get such information.

• I do not understand question exactly, but in case if you have list of addresses with a software that listen on some ports, try to connect there using eg. Socket class:

  Socket m_Socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
  m_Socket.Connect(serverEndPoint);
  

  and eventually try to catch an exception...

  If you have connection that are already made in you code you can check m_Socket.Connected property..