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Re: ipchains rules: REJECT vs. DENY



On Wed, 25 Jul 2001 13:38:19 EDT, Jason Healy writes:
<DENY vs. REJECT>
>The other problem is that if you DENY certain oft-used services, you
>can cause problems.  For example, if you DENY on the ident service
>port, machines trying to connect to you will timeout waiting for ident
>info.  Some mail servers try to connect back to the ident port on a
>client before accepting mail.  If your machine DENYs ident requests,
>it will have to wait for that timeout to occur before sending mail.
>
>Moral of that story is to make sure that you either run an ident
>server, or set it to REJECT.

Well, I wouldn´t (and don´t) run identd, since I have no intention of 
 revealing the name of the user running a particular service (in 
 general this will be either your login-name or root), but there are
 some interesting other options:

- accept connections to services like ident (or finger or..) but just 
 return random garbage. One option for this is via inetd:
 - ident stream tcp nowait nobody /bin/dd dd if=/dev/urandom bs=64 \
     count=1
- or, for ident specifically, use fakeidentd (see freshmeat.net, 
 excellent software).

Of course, you would want to log such connections via the 
 kernel-firewall, just so you´ll now what´s going on.

cheers,
&rw
-- 
-- Renting airplanes is like renting sex:  It's difficult to arrange
-- on short notice on Saturday, the fun things always cost more, and
-- someone's always looking at their watch.      - Paul Tomblin, asr
----


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