On Thu, 8 May 2025 18:43:37 +0200, Jan Klemkow wrote:
> On Thu, May 08, 2025 at 06:16:47PM +0200, Pascal Stumpf wrote:
> > On Thu, 28 Nov 2024 10:15:58 +0100, Jan Klemkow wrote:
> > > On Wed, Nov 27, 2024 at 06:32:23PM GMT, Pascal Stumpf wrote:
> > > > Continuing from misc@:
> > > > 
> > > > I have two different gateway machines, one with em(4), one with igc(4)
> > > > that exhibit the problem.
> > > > 
> > > > With an iked.conf policy like this:
> > > > ikev2 "foo" esp \
> > > >         from 192.168.5.0/24 to dynamic \
> > > >         [...] \
> > > >         peer any \
> > > >         [...]
> > > > 
> > > > where 192.168.5.1 is an address on the gateway itself and the default
> > > > route is on pppoe0 upon vlan7 upon em0/igc0.  TCP MSS is clamped in
> > > > pf.conf for the IPSec tunnel:
> > > > 
> > > > match on enc0 all scrub (max-mss 1228)
> > > > 
> > > > This works as expected for any machine on the 192.168.5.0/24 network.
> > > > However, TCP connections to 192.168.5.1 will receive huge return packets
> > > > that get fragmented over pppoe0.
> > > > 
> > > > Setting net.inet.tcp.tso=0 restores expected behaviour.  So there is a
> > > > bug somewhere when making the decision to rely on TSO for TCP
> > > > segmentation.
> > > 
> > > Interesting.  I'll have a look at this next week.
> > 
> > have you been able to find out anything?  This bug is still present in
> > -current, unfortunately.
> 
> Sorry.  I start reproduce you setup and stopped at PPPoE.
> Do you have an idea how to do this?
> 
> It this your communication path?
> 
> IPSec -> pppoe0 -> vlan0 -> em0 ---- igc0 -> vlan0 -> pppoe0 -> IPSec

Yes, although I'm not sure if the PPPoE bit matters in this case; FWIW I
can also reproduce this with:

IPSec -> pppoe0 -> vlan7 -> em0 ---- re0 -> IPSec

as well as

IPSec -> iwx0 --- [router that does pppoe] --- re0 -> IPSec.

and

IPSec -> iwx0 --- [router that does pppoe] --- igc0 -> vlan7 -> pppoe0 -> IPSec.

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