Hi Subhro,
Thanks for your reply

The reason I want the server to route between the internal network and the router is because I only want to allow specific clients out onto the internet, and I can't see how to do this with the router I've got. Plus, it's a good excuse to try to learn something new :-)

You say it's expected that I can't ping. It's things like this that confuse me, due to lack of understanding on my part, I've allowed all traffic through. Of so I thought...

I've had a quick skim of the HOWTO, and it seems informative. But, it's still the IPFW rules that get me all confused


Subhro wrote:

Hi Ben,

First of all I must say you explained your requirements very well. Not many
people can precisely say what they need. Bravo!

Let's get to the point now. First of all I d don't find a good reason why
you would like to introduce your system ( (Lets call it server)
to work as a router although you have a dedicated router. You can be well
off adding routes in the D-Link and be off with it. If you really want to
live with your current setup, then you must decide whether you want to go
with NAT or with transparent proxy. With your current setup, it is perfectly
all right that you can't ping any external hosts. I would recommend that you
go with NAT guarded by ipfw at the server. But you may also go with
transparent proxy as it has its own advantages. Refer to the following page:


This has a really good tutorial on setting up NAT


Subhro Sankha Kar
Indian Institute of Information Technology
Block AQ-13/1, Sector V
Salt Lake City
PIN 700091

-----Original Message-----
[mailto:[EMAIL PROTECTED] On Behalf Of Ben Quick
Sent: Wednesday, January 07, 2004 11:05 PM
Subject: IPFW confusion

Hello all,
I've been hunting around for information on IPFW, and how to set up the
rules I require. I found a tutorial that seemed to fit my needs:

However, I can't get the config to work. I've commented out all the deny
rules. In this instance, I can browse the web via SQUID that's installed
on the IPFW box. I can't browse the web directly, though. That is the
only external access I get. I can't ping any sites, DNS lookups fail
(I've set the DNS servers on the client workstation to be that my ISP's.
I also tried setting it to look at the IPFW box first, with no luck)

Can anyone offer help on this one? I'm getting stuck in a muddle of

My setup is as follows

Internal LAN is 192.168.0.x
IPFW machine has 2 NIC's:
rl1 connects directly to my DSL router (D-Link 504) which has an
internal IP of along with it's public IP on the DSL port

The ruleset I'd like is as follows

For client IP's of - allow the following
HTTP \ HTTPS - But not directly, force them to use SQUID (Listening on
port 8080, and using squidGuard for content filtering)
POP3 - But, only so far as pop.myisp.com
IMAP - But, only so far as imap.myisp.com
SMTP - But, only so far as smtp.myisp.com
DNS lookups - But, only with ns1.myisp.com and ns2.myisp.com
NNTP - But, only so far as news.myisp.com
FTP - To anywhere

For client IP's of - no access to anything
external to the 192.168.0.x network should be granted

I'd like the IPFW box and to be able to SSH out to anywhere.

I'd like to allow SSH inbound from a specific IP to be directed at the
IPFW box (The port forwarding can be done with the DSL router) - SSH
isn't currently listening on that interface, I'll get to that later :)

Does this sound like a reasonable ruleset? Is anyone willing to help me
generate it?


[EMAIL PROTECTED] mailing list
To unsubscribe, send any mail to "[EMAIL PROTECTED]"

Reply via email to