need help with pf configuration

[Victor Sudakov]

Matthew Seaman wrote:
> > 
> >>>> > > > I need no details, just a general hint how to setup such security
> >>>> > > > levels, preferably independent of actual IP addressses behind the
> >>>> > > > interfaces (a :network macro is not always sufficient).
> >>> > > 
> >>> > > You may use urpf-failed instead :network
> >>> > > urpf-failed: Any source address that fails a unicast reverse path
> >>> > > forwarding (URPF) check, i.e. packets coming in on an interface
> >>> > > other than that which holds the route back to the packet's source
> >>> > > address.
> >> > 
> >> > Excuse me, I do not see how this is relevant to my question (allowing
> >> > traffic to be initiated from a more secure interface to a less secure
> >> > interface and not vice versa).
> > Sorry, you can't do this with pf, ipf or ipfw (the 3 firewalls in
> > FreeBSD). There is no concept of security level at all, you must specify
> > on each interface the traffic allowed (in input and output).
> > 
> > My reply was about the use of the interface:network addresses.
> 
> pf has the concept of packet tagging.  So you can write a small rule to
> tag traffic crossing eg. your set of internal interfaces and then write
> one ruleset to filter all that traffic identified by tag.

Thank you again. Tags rule! The following excerpt illustrates the
concept I have tested in my lab:

pass in on $dmz from any to any tag FROMDMZ
pass in on $inside from any to any
block out on $inside tagged FROMDMZ

The second rule is required to create state for the return traffic to flow
from $dmz to $inside.

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov at sibptus.tomsk.ru