Re: 2.6.16-rc3 panic related to IP Forwarding and/or Netfilter

From: Jens Taprogge
Date: Thu Feb 16 2006 - 18:26:47 EST


On Thu, Feb 16, 2006 at 09:33:07PM +0100, Patrick McHardy wrote:
> Jens Taprogge wrote:
> > The two patches fix the panic. However routing still does not quite
> > work.
> >
> > My setup consits of two masquerading gateways with local adresses
> > 192.168.1.128 (2.6.15.1) and 192.168.3.11 (2.6.16-rc3 + patches). They
> > connect the two local networks through an IPSEC tunnel. With the exact
> > same setup that previously (192.168.3.11 running 2.6.13) worked I can
> > now only reach from 192.168.1.0/24 to 192.168.3.0/24 and not the other
> > way around:
> >
> > Pinging from 192.168.1.128 I am getting:
> > $ ping 192.168.3.15
> > PING 192.168.3.15 (192.168.3.15): 56 data bytes
> > 64 bytes from 192.168.3.15: icmp_seq=0 ttl=63 time=127.9 ms
> >
> > On the other hand pinging from 192.168.3.11 I am getting timeouts.
> >
> > This is even the case if I set the nat POSTROUTING rule to:
> > $ iptables -t mangle -I PREROUTING -p esp -j MARK --set-mark 111
> > $ iptables -t nat -F POSTROUTING
> > $ iptables -t nat -A POSTROUTING -o ppp0 -s 192.168.3.0/24 \
> > -m mark ! --mark 111 -j MASQUERADE
> >
> > on both sides of the tunnel which should disable masquerading for IPSEC
> > packages.
> >
> > However the tunnel works as soon as I completly disable masquerading.
>
> 2.6.16-rc includes patches for proper netfilter IPsec handling. Packets
> will now go through the chains once in plain text and once encrypted,
> so I guess you're masquerading the packets that should go through the
> tunnel to an address that doesn't match the policy anymore and they
> are therefore not handled by IPsec (this is also the case my patches
> fixed). So you need to make sure you don't have any SNAT rules that
> change the unencrypted packets to an address not included in the policy.

Thanks. That pointed me in the right direction. After excluding the
plain-text IPSec traffic from masquerading things work again.

Best Regards
Jens Taprogge
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