Re: IPv6 and private net with masquerading not working correctly

Re: IPv6 and private net with masquerading not working correctly

[Cong Wang]

(Cc'ing netdev and netfilter-devel)

On Fri, Aug 7, 2015 at 6:00 AM, Gerhard Wiesinger <lists@wiesinger.com> 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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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@wiesinger.com> 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/
>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
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> Please read the FAQ at  http://www.tux.org/lkml/