PF firewall rules and documentation

Patrick Lamaiziere patfbsd at
Mon Jan 31 10:31:00 UTC 2011

Le Sat, 29 Jan 2011 12:39:18 +1000,
Da Rock <freebsd-questions at> a écrit :

> I spent some time playing with pf and pf.conf, and followed the 
> directions in the handbook. It redirected me to the openbsd site for 
> pf.conf, and recommended it as the most comprehensive documentation
> for pf.
> Firstly, I didn't find that. I had to translate the instructions into 
> the current version used in FreeBSD, OpenBSD appears to be further 
> advanced than this based on the current docs.

Yes, you should refer to the OpenBSD 4.1 Packet FAQ :

> Secondly, some of the rules don't appear to be following. From my 
> understanding based on the documentation in the handbook and on the
> site pf is default allowing traffic. 

According to a current discussion on misc at It allows
traffic to pass but without creating states.

> So explicit rules to block
> should be set first and then rules set to allow what is needed in.
> Some assumptions are made in the rules by the interpreter, so
> according to OpenBSD one can (even in the older versions) simply
> state block and it is interpreted as 'block on $interfaces all'. This
> turned out to not be the case.

Ah? Do have an example for this?
> I know this has come up before, but I think it might be time to
> document pf.conf properly. It seems to be a bit of security risk not
> to. Users may be mistaken in their belief of their security on the
> network using pf, and may be less likely to trust again when it
> breaks.

This is true, many things are now more precise in the manual page of
OpenBSD's PF. But it will be hard to merge only these precisions in our
pf.conf manual page.

There are some plans to update PF to a more recent version. So may
be it will be better.


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