Re: [SLUG] More Firewall Fun

From: Brian Coyle (brianc@magicnet.net)
Date: Thu Jul 05 2001 - 23:48:30 EDT


Russell Hires wrote:
>
> I've got some questions...
> I guess this is to Derrick, but anyone else feel free to chime in...
>
> First, what were the services you disabled? The HOWTOs say time and
> discard and a few others are internal services. What do they do?

Disable EVERYTHING you're not using. If you don't know what it is,
you're probably not using it. ;)

That said, here's what `man inetd` says:

  Inetd provides several ``trivial'' services internally by use of
routines
  within itself. These services are ``echo'', ``discard'', ``chargen''
  (character generator), ``daytime'' (human readable time), and ``time''
  (machine readable time, in the form of the number of seconds since
mid-
  night, January 1, 1900). All of these services are tcp based. For
de-
  tails of these services, consult the appropriate RFC from the Network
In-
  formation Center.

>
> Second, what software did you use to scan the other machine that you
> pointed out that didn't have some of those services disabled?

nmap (www.insecure.org/nmap/ ) and nessus (www.nessus.org) are two
of the most popular scanning tools.

> Third, where do you keep the ipchains script? For me, it seems that Debian
> has got some default rules and thus a default script, but I don't exactly
> know where to find it...

Not exactly sure of the file name for Debian, but try

        $ grep ipchains /etc/init.d/*

> well, I guess I don't need to know to edit it,
> because there is a utility called, aptly, "ipchains," so I should just be
> able to type (from the command line) "ipchains -A <chain>", at least
> according to the man page...

Yeah, but if you add the chains manually, they'll be gone after a
reboot.

-- 
'If everyone climbs Mt. Everest because it's hard to do, why do they
go up the easy side?' -- George Carlin



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