Re: Company Firewall's IP Address

From: Bradley D. Moore (brad.moore@circlecity.net)
Date: 11/15/02

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    From: "Bradley D. Moore" <brad.moore@circlecity.net>
To: security-basics@securityfocus.com
Date: Fri, 15 Nov 2002 13:04:21 -0500

    If the IP address shown was that of your firewall, then your firewall must be
    running NAT. If this is the case, then your network admin is correct. Fir
    the firewall to be more stealthy, it would need to be running in bridged (not
    routed) mode, which precludes the use of NAT and requires a) your machine have
    a globally unique IP address ( in which case *that* would have been the
    address shown), or b) some other (routing) device run NAT.

    An important point Steve makes is that SOME IP address must always be known to
    any host you connect to, or communications cannot occur. Which address(es)
    are divulged is entierly a question of network design.

    -------------------------------------
    If I were to walk on water, the press would say I'm only doing it
    because I can't swim.
                    -- Bob Stanfield
    -------------------------------------
    Bradley D. Moore, CNE, CCNE, CCNA
    brad.moore@circlecity.net
    317-331-7168
    -------------------------------------
    PGP Public Key: http://www.circlecity.net/brad.moore.asc
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    ---------- Original Message -----------
    From: Steve Cooper <steve@nuclear-monkeys.co.uk>
    To: tony tony <tonytorri@yahoo.com>
    Sent: 13 Nov 2002 21:40:17 +0000
    Subject: Re: Company Firewall's IP Address

    > On Tue, 2002-11-12 at 22:09, tony tony wrote:
    > > I was doing security research on the internet at work yesterday....when
    all of
    > > a sudden I got a pop up advertisement that stated that I was broadcasting
    my IP
    > > address to the entire internet. It then showed a screen with my IP address
    > > which was the the external IP interface of one of our companies firewalls.
    > >
    > > It just bothers me that someone would be able to determine the IP address
    of
    > > our firewall that easily. It seems to me that our firewall should operate
    in a
    > > more stealth mode. Our firewall administrator said it is not technically
    > > possible to do this. What is your take?…I am not a checkpoint firewall
    guru…so
    > > I do not know. All I know is that if I was a hacker, I would love to
    hammer
    > > away on an ip address that represented a firewall.
    > >
    > > Click on the following to learn more about this pop up site.
    > >
    > > http://www.bonzi.com/internetalert/ia99m.asp
    > >
    > >
    > > __________________________________________________
    > > Do you Yahoo!?
    > > U2 on LAUNCH - Exclusive greatest hits videos
    > > http://launch.yahoo.com/u2
    > >
    >
    > Your admins right, your IP has to be known in order for information to
    > be returned from the internet to you and a companys external IP's are
    > easy to find with legal tools and websites like samspade.org or whois
    > queries with domain registrars.
    > It's the ports that are open on your IP address that are the real
    > danger, in order to hack your PC an attacker will need some ports open
    > so they can send information through those ports. If your firewall is
    > securely configured and you don't host any web or mail servers that
    > allow trafic inside then you should be ok.
    ------- End of Original Message -------

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