Question

If I were to have the TcpClient as the value what would a good value for the key be? IP address? Static counter variable incremented for each connection?

Is there not a better way to find the IP address of a tcp client rather than this?

client.Client.RemoteEndPoint.ToString()

What do most people usually use?

Answer 1

To identify a client see http://blogs.msdn.com/b/mariya/archive/2006/06/19/636437.aspx .

As key for the Dictionary I would use

string MyDictKey = client.Client.RemoteEndPoint.Address.ToString()  + ":" + client.Client.RemoteEndPoint.Port.ToString();

BTW: if your server is multi-threaded I would strongly recommend using a ConcurrentDictionary.