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Date:      Sun, 27 Sep 1998 10:11:49 +1200 (NZST)
From:      Andrew McNaughton <andrew@squiz.co.nz>
To:        Muhammad Najib <najib@csi-x.net>
Cc:        freebsd-security@FreeBSD.ORG
Subject:   Re: Firewall ...
Message-ID:  <Pine.BSF.3.96.980927100538.390D-100000@aniwa.sky>
In-Reply-To: <360cc91e.bbd.0@csi-x.net>

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On Sat, 26 Sep 1998, Muhammad Najib wrote:

>     Could you please give me an example file as well as some lines which have
> the rule(s) of allowing connection on the telnet port(23) and deny any other
> else than that. I've refered to the page you pointed me to, but I just wanna
> make a kinda confirmation here :) . Which where if I were to use ipfw :
> 
> ipfw add pass tcp from any to any 23

allows all telnet connections in and out.

If you only wanted to enable incoming telnet connections you could use:

ipfw add pass tcp from any to any 23 recv
ipfw add pass tcp from any 23 to any xmit


> ipfw add pass tcp from any 23 to any

allows anything in and out so long as it comes from a port 23.  This is
bad.  If they have root on their end then they can send a packet to any
port on your machine.  (They may not get anything back).

> ipfw add deny all from any to any
                ^^^
change 'all' to 'ip'.


Andrew McNaughton


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