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Date:      Fri, 21 Apr 2000 11:17:34 -0400
From:      "Jason Portwood" <jason@iac.net>
To:        <freebsd-security@FreeBSD.ORG>
Subject:   RE: log-in-vain [ was: 10 days ]
Message-ID:  <6381A6A8826BD31199500090279CAFBA106958@FOGHORN>
In-Reply-To: <6381A6A8826BD31199500090279CAFBA0D8BC2@FOGHORN>

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>
> > Something you might want to do, if you haven't already, is enable
> > log_in_vain in /etc/rc.conf by adding 'log_in_vain="YES"'.
> > It will log connection attempts on ports that have nothing listening on
> > them. It can be very enlightening.
>

Same thing goes for logging ipfw on the rejects.  It's interesting sometimes
to fire up
another IP alias and see the people scanning by...

> but what does one *do* with the info?  there is so much scanning and so
> many baby cracker attempts that it does little good writing to source
address
> admins.  and the sources are spoofed in the majority of the cases anyway.

The best defense is to have as much control or rather restriction as
possible over
what goes on.  If it's not needed why have it running.  If a service on a
machine
only needs to talk to one other machine use ipfw and restrict it.  Every
little bit helps.

Then sit back, keep things up to date, watch the mailing lists for bugs, and
just watch what's
going on.  Like with spam you probably don't send complaints about everyone
of them.

>
> while i think log watching is important, it can be massive
> data.  so i try to keep it down to those data about which i can do
something,
> either by changing my defenses or by dealing with the source of the
problem.
>

I saw something mentioned a while back on the list that might be of help.
It was a program
that would watch for network scanners.  Then when one was found scanning
around it would send
a route packet to your core router to forward all traffic from that scanners
IP to the scan watching machine.  The server then would route the detected
scanner to I believe a null device or just let the scanner rescan that box
again.  You would just route small chunks of your network(s) to the scan
detection machine.  I thought it sounded great but haven't had the time to
contact the author about it.

I don't recall any further discussion on it but what do others think about
that?  Curious to know...

Jason Portwood - jason@iac.net
Systems Administrator - Strategic/Internet Access Cincinnati
Sales and Tech Support - 513-860-9052




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