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Date:      Thu, 06 Oct 2016 15:01:23 +0200
From:      Mark Martinec <Mark.Martinec+freebsd@ijs.si>
To:        freebsd-pf@freebsd.org
Subject:   Re: dscp set/get
Message-ID:  <bbfc73f2096ac204a752a800c2863e97@mailbox.ijs.si>
In-Reply-To: <C539471F-8C0C-4BCD-815C-D449EF1427DB@FreeBSD.org>
References:  <57F5D9D2.1060103@norma.perm.ru> <311888F1-3BD6-4C4E-818D-C4A9C00B55ED@FreeBSD.org> <C1F20DD6-5B32-4856-A2F7-7DAFB38E4D3A@lastsummer.de> <C539471F-8C0C-4BCD-815C-D449EF1427DB@FreeBSD.org>

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Just adding recognition to a parser for a couple of DSCP constants
to be mapped to TOS is not the solution. Keep in mind that DSCP
is a 6-bit field, and TOS is an 8-bit field. The remaining two bits
are used for ECN (Explicit Congestion Notification).

Setting TOS field with the intention of changing DSCP
clobbers ECN bits.  Pf needs a proper support for DSCP,
currently it is unusable for this purpose in FreeBSD
(one can use the PF from OpenBSD).

   Mark


2016-10-06 11:03, je Kristof Provost napisal
> On 6 Oct 2016, at 10:30, Franco Fichtner wrote:
>>> On 06 Oct 2016, at 10:10 AM, Kristof Provost <kp@FreeBSD.org> wrote:
>>> 
>>> On 6 Oct 2016, at 6:57, Eugene M. Zheganin wrote:
>>>> pf still lacks the DSCP handling, will it be difficult/expensive to 
>>>> add
>>>> this ? AFAIK ipfw got this recently.
>>>> 
>>> pf has set-tos and tos keywords. What is it not letting you do?
>> 
>> I think it works already with the plain hex/decimal values given,
>> though we're missing OpenBSD's parser support for special DSCP
>> options with its funky naming:
>> 
>> "This rule applies to packets with the specified TOS bits set. string
>> may be one of critical, inetcontrol, lowdelay, netcontrol,throughput,
>> reliability, or one of the DiffServ Code Points: ef, af11 ... af43,
>> cs0 ... cs7; number may be either a hex or decimal number."
>> 
>> http://man.openbsd.org/OpenBSD-current/man5/pf.conf.5
>> 
>> Looks like pfctl(8) is the only thing to "fix" here.  I'll take a 
>> look.
>> 
> Oh, yes, if you want those constants that should be a straightforward 
> port of
> their changes to parse.y. I have no objections to including that.  It’s 
> another
> (small) step in bringing our pf closer to openbsd pf.
> 
> Regards,
> Kristof



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