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Date:      21 Oct 2000 19:49:16 -0000
From:      vladimir@math.uic.edu
To:        bartequi@inwind.it, freebsd-stable@freebsd.org
Subject:   Re: ipfw advice needed
Message-ID:  <20001021194916.21624.qmail@math.uic.edu>
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	>From bartequi@inwind.it Sat Oct 21 18:49:56 2000
	>Delivered-To: vladimir@math.uic.edu
	>From: Salvo Bartolotta<bartequi@inwind.it>
	>Date: Sat, 21 Oct 2000 19:48:43 GMT
	>Subject: Re: ipfw advice needed
	>To: vladimir@math.uic.edu
	>X-Priority: 3 (Normal)
	>MIME-Version: 1.0
	>Content-Transfer-Encoding: quoted-printable
	>
	>>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<
	>
	>On 10/21/00, 7:22:40 PM, vladimir@math.uic.edu wrote regarding ipfw=20
	>advice needed:
	>
	>
	>> Dear -STABLE users,
	>
	>> I am trying to setup ipfw rules to protect some
	>> of our crucial machines, including a file server.
	>> The system is 4.1.1-STABLE.    So far I've been
	>> using access lists on the router, but would like
	>> to get some extra security on the machine itself.
	>> One thing got me confused:  there is a couple of
	>> daemons that are listening on the ports not
	>> listed in /etc/services.   For example, (lsof output):
	>
	>> ypserv      126   root    5u  IPv4 0xcefe2d80      0t0  TCP *:1023=20
	>(LISTEN)
	>> ypbind      128   root    5u  IPv4 0xcefe2b60      0t0  TCP *:1022=20
	>(LISTEN)
	>> mountd      135   root    4u  IPv4 0xcefe2940      0t0  TCP *:1021=20
	>(LISTEN)
	>> nfsd        137   root    3u  IPv4 0xcefe2720      0t0  TCP *:nfsd=20
	>(LISTEN)
	>> rpc.lockd   161   root    4u  IPv4 0xce898900      0t0  UDP *:lockd
	>> rpc.lockd   161   root    5u  IPv4 0xcefe2500      0t0  TCP *:lockd=20
	>(LISTEN)
	>> rpc.lockd   161   root    9u  IPv4 0xce89a6c0      0t0  UDP *:855
	>> rpc.statd   163   root    3u  IPv4 0xce898840      0t0  UDP *:990
	>> rpc.statd   163   root    4u  IPv4 0xcefe22e0      0t0  TCP *:1020=20
	>(LISTEN)
	>
	>
	>> ypbind listens on ports 1022, mountd on tcp port 1021, ypserv on tcp
	>> port 1023, statd on port 1020.    What do I do with those?
	>> Are these ports officially assigned or are they arbitrarily selected
	>> by these daemons when they start and register with the portmapper?
	>> Is there a range of TCP ports that I should keep opened for
	>> incoming connections for these services to operate properly?
	>> Any hints would be appreciated.
	>> Thanks you!
	>>       Vladimir
	>
	>
	>
	>The short answer is portmap(8), ypserv(8), ypbind(8); also, some=20
	>material is found in the handbook (in particular, cf Security; cf=20
	>Advanced Networking).
	>
	>Golden service rule: if you don't need them, nuke them. In order to=20
	>nuke them: cf ps(1), kill(1), rc.conf(5).
	>
	>N.B. I am not a security expert; rather, I am RTFMing the subject :-)
	>Somebody else will give you tips as to the most appropriate policy.
	>
	>HTH a little,
	>Salvo

Hi Salvo, 
thank you very much for the reply,  but I think you misunderstood me a
little.  We do need these services, because the machine in question is
an NFS server and a yp slave (sorry I was not specific about that). I
understand that ypbind has decided to listen on port 1022 and
registered that with the portmapper,    but  I guess what I wanted to
know -- is there any way to control this choice of a port number?  I
could not find any relevant documentation on that (I apologize if the
answer is somewhat obvious).  

Thanks,
	Vladimir


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