Date: Mon, 21 Dec 2009 11:10:13 +0000 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: DAve <dave.list@pixelhammer.com> Cc: 'User Questions' <freebsd-questions@freebsd.org> Subject: Re: Source of closed port RST responses Message-ID: <4B2F5795.5010206@infracaninophile.co.uk> In-Reply-To: <4B2EA349.3050604@pixelhammer.com> References: <4B2E7CEA.1020502@pixelhammer.com> <4B2E8628.6060100@radel.com> <4B2EA349.3050604@pixelhammer.com>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig5779AA1B5EE1DF245192B370 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable DAve wrote: > I will be installing pf this week, I just need to write up my rule sets= > for these servers. I had been working on the webservers first. Is there= > a rule I can use to log connection attempts to closed ports? pf doesn't really know anything about whether there is a listener at a pa= rticular port or not. However, you can log suspicious traffic using a 'capture ev= erything' rule, which should log and then block or drop all traffic that matches it= =2E You then override that with more specific rules to allow the traffic to the servic= es you want to publish on the net. [pf is a 'last matching rule wins' type firewall, = so you write the rules in order from most generic to most specific.] Something like th= is: ext_if=3D"em0" # alter to match your hardware set skip on lo0 set loginterface $ext_if set state-policy if-bound scrub in block log all pass in on $ext_if proto tcp from any to $ext_if port http flags S/SA kee= p state [...] (You'll need more pass rules than that -- especially to allow your host t= o do things like query the DNS, allow SSH in and out, connect to remote web/ft= p sites, etc.) Remember to run pflogd to have the logged packets saved to disk. Be awar= e that the log output in /var/log/pflog is actually in pcap format, so you'll need t= o use tcpdump -r /var/log/pflog to turn it into something human readable. /var/= log/pflog can get recycled fairly rapidly depending on network conditions. Or you = can just run tcpdump -i pflog0 to get a live view of rejected packets. Cheers, Matthew --=20 Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard Flat 3 PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate Kent, CT11 9PW --------------enig5779AA1B5EE1DF245192B370 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEAREIAAYFAksvV5wACgkQ8Mjk52CukIzv9QCeNPrPUfB/mSnIbPEPWwGAiW7Q Ay4AoIB6e2v58n2+1Rvj8gnHFMPlhSv0 =kjj/ -----END PGP SIGNATURE----- --------------enig5779AA1B5EE1DF245192B370--
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