On Thu, May 14, 2009 at 11:18:47AM +0800, W B Hacker wrote:
> >> Using p0f with the barest of directives:
> >>
> >> p0f -i vr0
> >>
> >> What am I doing wrong w/r p0f & Exim?
> >>
> >> Does p0f need Exim to do a 'delay' before rejection in order to ascertain
> >> the caller's OS?
> >
> > I've been using p0f for a while (> 1 year I think) with no problems. p0f
> > runs
> > "passively" and then Exim queries it via a ${perl expansion (though I
> > suppose
> > if I wanted to I could write a kind of exim-to-p0f proxy and use a plain
> > ${readsocket instead).
> >
> > Currently all I'm doing with it is querying p0f from exim and logging the
> > results - the results don't actually /affect/ anything (except the contents
> > of
> > the log). But to that extent, it works just fine.
I run p0f simply as
p0f -i ethX -Q /path/to/socket -u p0f \
'(tcp[tcpflags] & (tcp-syn|tcp-fin|tcp-rst) != 0) and not ether src
XX:XX:XX:XX:XX:XX'
where XX:XX:XX:XX:XX:XX is the MAC addr of the ethX interface. Mine is a
quiet system, and it shows no signs of failing to query p0f.
That said, (a) it is a /very/ quiet system and (b) I've never really looked
into p0f's -c/-e/-M options.
If I was running this on a busy system and there were signs of trouble I'd
probably look to the -c option first, and also observe p0f's exit stats
messages (see man p0f, "P0f, when run without -q, also reports average packet
ratio on exit").
--
Dave Evans
http://djce.org.uk/
http://djce.org.uk/pgpkey
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