Re: IPv6 and private net with masquerading not working correctly

[Gerhard Wiesinger]

Any update on this issue?

Thank you.

Ciao,
Gerhard

On 10.08.2015 19:39, Cong Wang wrote:
> (Cc'ing netdev and netfilter-devel)
>
> On Fri, Aug 7, 2015 at 6:00 AM, Gerhard Wiesinger <lists@xxxxxxxxxxxxx> wrote:
> > On 06.08.2015 20:43, Gerhard Wiesinger wrote:
> > > Hello,
> > >
> > > I'm having the following problem with IPv6 and a private internal LAN
> > > which will be masqueraded to the public internet (I don't want to have
> > > public IPs in the LAN because of some static IPs and tracking) . Rules are
> > > generated by shorewall.
> > >
> > > Problem is that ICMP6 packets source address is not translated by the
> > > kernel on the reply when MTU has to be discovered because of too big packets
> > > and limited MTU capabilities on the path (happens also on tcp6 which works
> > > thereofore not correctly).
> > >
> > > # From an internal host on net fd00:1234:5678::/64
> > > ping6 -s 2000 2a02:1234:5678:7::2
> > >
> > > /etc/shorewall6/masq
> > > EXT_IF                   fc00::/7
> > >
> > > ip6tables rule:
> > > MASQUERADE  all      *      *       fc00::/7             ::/0
> > >
> > > # Internal interface
> > > IP6 fd00:1234:5678::9 > 2a02:1234:5678:7::2: frag (0|1432) ICMP6, echo
> > > request, seq 1, length 1432
> > > IP6 fd00:1234:5678::9 > 2a02:1234:5678:7::2: frag (1432|576)
> > > IP6 2a02:1234:5678:9abc::115 > fd00:1234:5678::9: ICMP6, packet too big,
> > > mtu 1440, length 1240
> > >
> > > # External interface
> > > IP6 2001:1234:5678:9abc::1 > 2a02:1234:5678:7::2: frag (0|1432) ICMP6,
> > > echo request, seq 1, length 1432
> > > IP6 2001:1234:5678:9abc::1 > 2a02:1234:5678:7::2: frag (1432|576)
> > > IP6 2a02:1234:5678:9abc::115 > 2001:1234:5678:9abc::1: ICMP6, packet too
> > > big, mtu 1440, length 1240
> > >
> > > Looks to me like a a major kernel bug.
> > > Kernel version is: 4.1.3-201.fc22.x86_64 from Fedora 22
> > >
> > > Any ideas?
> > Any comments?
> >
> > Ciao,
> > Gerhard
> >
> > --
> > http://www.wiesinger.com/
> >
> >
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