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Date:      27 Nov 2002 09:20:46 -0500
From:      Dan Pelleg <daniel+bsd@pelleg.org>
To:        freebsd-ipfw@freebsd.org
Subject:   IPFW2 keepalives only work in one direction?
Message-ID:  <u2sof8b3xhd.fsf@gs166.sp.cs.cmu.edu>

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I'm trying to track down a problem with IPFW2 where stateful connections
time out. net.inet.ip.fw.dyn_keepalive is set to 1. This a host that can
SSH out and also accepts incoming SSH connection. The relevant rules are:

allow tcp from ${friendlynet} to me dst-port 22 setup
allow tcp from me to any keep-state

What I'm noticing is that:
 - if I ssh out, IPFW2's keepalives will keep the connection alive (the
timeout counter on it will jump up if the connection is left idle)
 - if I ssh *in*, the connection will be made, but will time out if left idle.

 Now, if the following two rules are changed to:
allow tcp from ${friendlynet} to me dst-port 22 setup keep-state
allow tcp from me to any keep-state

 then neither type of connection times out.

 What's going on? I understand that in the first configuration the stateful
rules are associated with the second rule (since they're generated by the
reply packet). But still - the dynamic rule is installed, so ipfw should
keep it alive just the same, no?

This is -STABLE as of Nov. 16

-- 

  Dan Pelleg

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