Originally Posted by malbuc87uk
I'm not much of an expert but...
If you start a file transfer, and run netstat, one of the open connections is a direct connection to his IP.
I know no more than that, you'd have to Google it, but that's what I know.
For AIM it will be port 4443 ... i'm not sure about the other IM clients
It may allow direct connection and yes it will be in an open connection when doing netstat but there have been features which can prevent this, in the new client of msn messenger released not too long ago, they had the option of not allowing people to connect directly to each other and let all the information go via the msn servers, therefore, countering this technique, yet again, i am not sure about the other IM clients