Hi Eric, On Wed, Mar 20, 2013 at 09:18:21PM -0600, Eric Blake wrote: [...]
By looking at the changes you made:
--A FI-vnet0 -p tcp -m tcp --sport 110 -m conntrack --ctstate ESTABLISHED -m conntrack --ctdir ORIGINAL -j RETURN +-A FI-vnet0 -p tcp -m tcp --sport 110 -m conntrack --ctstate ESTABLISHED -m conntrack --ctdir REPLY -j RETURN
The first rule looks wrong to me indeed, traffic coming in the original direction will initiate the connection to destination port TCP/110. Therefore, your change is correct.
Correct for the new kernel interpretation, but we also want to support use of libvirt with older kernels, preferably with a runtime check so that a binary compiled on an older kernel will still work after a kernel upgrade.
My suggestion is to relax that rule-set that you're using, ie. remove the --ctdir. The connection tracking table and the TCP tracker already take care for those invalid situations that you were trying to catch with that --ctdir. You only have to add an iptables rule somewhere to catch invalid packets. I can also pass that patch to -stable starting 2.6.32 if that helps, but you will still have to fix your rule-set.