How does CP determine IDLE timeout?

From:	"Wesley K. Joyce" <wjoyce at uvi dot edu>
To:	<m0n0wall at lists dot m0n0 dot ch>
Subject:	How does CP determine IDLE timeout?
Date:	Mon, 20 Feb 2006 08:03:10 -0400

How does the CP determine the idle timeout?  Is it any packet that touches the inside interface
(such as ping 192.168.1.1) or any packet that passes through (routed, such as ping www.cisco.com)
that resets the idle timeout?