Firewall Wizards mailing list archives

Re: Pix 501 configuration question


From: "Victor B. Williams" <vbwilliams () essvote net>
Date: Fri, 7 Nov 2003 11:45:19 -0600 (CST)

I think the question we're all going to ask is...

Why in the world would you want to do something like this?  There's no
rhyme or reason why you would want internal people connecting to an
external IP address of a machine that already has an internal address
on your network...and quite frankly, I don't think you can do that
anyway.

If the point of the exercise is to access the machine by domain
name--whether inside the network or outside--then you need to use a
split dns setup...and that has nothing to do with the firewall. 
That's something that is isolated to your DNS setup.

If you're using BIND 8 or later, it's pretty straightforward...consult
the Oreilly BIND and DNS book.  If your DNS is Windows, I can't help
you there.

Adam Lang said:
This is probably an extremely basic question for this forum, but in an
hour of looking I haven't found a better forum to ask in, except
paying
multiple hundreds of dollars to call up Cisco and ask them.

I'm a total firewall newbie, and have just set up my first one for my
company, a Pix 501.  I think I did a fairly good job of it, all things
considered, but there's one thing that I just can't figure out.

A secondary company web server is behind the firewall, as are our
secondary DNS and two publicly available WebDAV servers.  These
machines have been given one-to-one NAT... 123.456.789.195 maps to
192.168.1.195, for example, for the web server.  This works fine from
the outside... anyone can connect to 123.456.789.195 on the web port
(and can't connect on any other port).  And from the inside, of
course,
anyone can connect to 192.168.1.195 on any port.  However, I want my
fellow employees to be able to connect to 123.456.789.195 from INSIDE
the firewall.  Hacks like the name-server-substitution stuff (where
the
Pix substitutes 192.168.1.195 for the 'real' address when the lookup
passes through the firewall) are just not going to cut it.

Is this possible?  Why doesn't it work in the first place... is there
something inherently insecure about allowing people from inside to
connect to an inside machine's external ip?  The pix is
123.456.789.195, and I can't imagine why it can't talk to itself.  Do
I
need to set up some sort of default routing?  Do I need to somehow
make
a rule translating 123.456.789.195 to 192.168.1.195 on the inside,
even
though the setup tool doesn't appear to allow you to do that?  (Maybe
I
need to do it from the command line?)  Do I need to ditch the Pix
because it just can't do this?  (Please say no.)

Thanks in advance for your help.

--Adam Lang

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"Real men don't even use monitors! I've just got a guy that can draw
real fast."

Victor Williams
Network Architect
Election Systems & Software
http://www.essvote.com
vbwilliams () essvote net
(402) 970-1100

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