Skip site navigation (1)Skip section navigation (2)
Date:      Wed, 5 Mar 2014 10:26:32 -0300
From:      Raimundo Santos <raitech@gmail.com>
To:        Andreas Nilsson <andrnils@gmail.com>
Cc:        FreeBSD Net <freebsd-net@freebsd.org>
Subject:   Re: ipfw / routing issue on 9.2-RELEASE
Message-ID:  <CAGQ6iC8-rXTerGBULzm1qo5it4tBnqL89eJn8-9kacsYaMRF%2Bg@mail.gmail.com>
In-Reply-To: <CAPS9%2BSsbPsQLqu9mwz7nhcn%2BjMkkj57JUeHOO3U5xm9eXLYb8g@mail.gmail.com>
References:  <CAPS9%2BSsbPsQLqu9mwz7nhcn%2BjMkkj57JUeHOO3U5xm9eXLYb8g@mail.gmail.com>

next in thread | previous in thread | raw e-mail | index | archive | help
Hello, Andreas.

If table(12) is empty, how will fwd know where to send the packets that
hits it?

Best regards,
Raimundo


On 4 March 2014 02:58, Andreas Nilsson <andrnils@gmail.com> wrote:

> Hello,
>
> I'm having a strange problem with ipfw and/or routing. I've only tested
> this on 9.2-RELEASE-p3, amd64. The machine is sort of acting as router. The
> ruleset is like (ipfw defaults to accept):
>
> $cmd="ipfw -fq "
>
> $cmd add 1 skipto 65534 log all from "table(1)" to any in recv "table(8)"
>
> ...
>
> $cmd add 65534 fwd tablearg all from "table(12)" to any
>
> Table 1 contains prefixes that should skip the normal rules and just pass
> through the box.
>
> Table 8 contains interface names.
>
> Table 12 is empty (so far).
>
> What happens is that packets that trigger the first rule never get to their
> destination. After looking at /var/log/security is see that packets trigger
> the rule, "never to be seen again". There is a route (ie not default) for
> the destination, but a tcpdump on the corresponding interface shows
> nothing.
>
>
> On changing the ruleset to
> $cmd="ipfw -fq "
>
> $cmd add 1 skipto 65533 log all from "table(1)" to any in recv "table(8)"
>
> ...
>
> $cmd add 65533 fwd x.y.z.w ip from "table(1)" to any in recv "table(8)"
>
> $cmd add 65534 fwd tablearg all from "table(12)" to any
>
> packets get to where they should.
>
>
> Why do I need the explict fwd rule? As far as I can see the ipfw man page
> says nothing about skipto changing the packets, and since the 65533 rule in
> the second ruleset triggers on the same thing as the skipto rule it would
> seem like packets are "intact". Why does the kernel not forward those
> packets?
>
>
> Best regards
>
> Andreas Nilsson
> _______________________________________________
> freebsd-net@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
>



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAGQ6iC8-rXTerGBULzm1qo5it4tBnqL89eJn8-9kacsYaMRF%2Bg>