ipfw nat drops icmp packets from localhost

Oleg Strizhak oleg at pcbtech.ru
Thu Oct 6 11:48:34 UTC 2011


Здравствуйте, Alexander V. Chernikov!

Вы писали 06.10.2011 15:16:

> On 06.10.2011 14:42, Oleg Strizhak wrote:
>> Hello, Andrey V. Elsukov!
>>
>> You wrote on 06.10.2011 at 13:38:
>>
>>> On 06.10.2011 12:29, Oleg Strizhak wrote:
>>>> After an investigation I've found out a very strange situation
>>>> - it seems to me, that ipfw nat drops some (type 11?) icmp
>>>> reply packets, whose udp request packets it hasn't
>>>> rewritten/seen before, e.g:
>>>>
>>>> So, I wonder whether someone else has seen the same case under
>>>> the similar circumstances? Isn't it a bug within ipfw nat
>>>> module and is there any work-around/patch for that? I've surely
>>>> googled, but in vain =( The only thing, that seems alike to my
>>>> problem, is http://www.freebsd.org/cgi/query-pr.cgi?pr=129093,
>>>> but the patch for 8 branch didn't cure anything =(
>>>
>>> Can you describe how you did apply and test this patch?
>>
>> in a usual way =) Unfortunately, copy-pasted from the mentioned
>> above page patch couldn't be applied w/ error:
>
> svn diff -c 223835 svn://svn.freebsd.org/base/stable/8>  ~/r223835.diff
> Can you try the patch attached (just to be sure) ?

sure, I can =) I'll try and then drop you a line about the results.

> This is exact situation from this (and some related PRs) and this
> revision definitely fixes it.

Sounds promising! Hope I've missed or neglected something, and that'd help.

> Btw, what is the value of net.inet.ip.fw.one_pass sysctl ?

now it's 0. As far as I remember, I've raised one_pass to 1 -- without 
any effect on the packets filtering (in my case)

> Are you sure that ipfw is the single enabled firewall on this machine
> ? Are you sure that system is using new kernel ?

Just 10 minutes ago I was quite sure in both cases, without any doubt..
Now, as the patch you've sent to me is char-to-char the same as mine...
I'll try once more.
Thanx for help and directions!

WBR,
Oleg

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