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RE: Yahoo Messenger Stale Sessions
From: <Leonard.Ong () nokia com>
Date: Wed, 13 Nov 2002 13:50:49 +0800


Yet, the OS should perform cleanup by implementing a tcp timeout ( default 3600 seconds ).  There are many protocols 
that doesn't send a FIN packet, yet they manage to terminate the session.

Leonard Ong
Network Security Specialist, APAC

Email.  Leonard.Ong () nokia com
Mobile. +65 9431 6184
Phone.  +65 6723 1724
Fax.    +65 6723 1596

Hmm, I'm not an expert in this, but I do realize if the 4-way handshake for
terminating a connection is not done properly, e.g. the user switched off
his dial-up modem abruptly, it would cause the "stale/zombie" sessions
described as above. The dial-up machine will not have the opportunity to
send the FIN to your machine.

You probably need to know the sequence number, source port, destination port
as well as source IP and destination IP (which you should know).

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