[CentOS] Centos firewall/router issue

Thu Feb 22 20:00:59 UTC 2007
Dustin Krysak <d.k.emaillists at gmail.com>

Good day everyone. Today has been "one of those..." days. So I have a
feeling this is just a brain lapse here.

At any rate, I am setting up a firewall/router using centos 4.4
(minimal install, yummed up to date).

I have in fact enables V4 ip forwarding (by editing /etc/sysctl.conf)
and rebooted the system. I use fwbuilder for my rules, and at this
point have a next to nothing set of rules. a DHCP server is also
residing on this router.

Now the firewall can get pings back from various sources on the net by
IP and by host name. The firewall can also ping the workstations, and
the workstations can ping hte firewall (VIA the internal IP). The work
stations are in fact getting proper IP info from the DHCP server (I
have released and renewed it many times as well as rebooted).

Now the issue is, I can not get out of the internal network to the
internet for any traffic. Pings (by ip and name), web sites, etc.

It "seems" like the traffic is not being forwarded, but I have run the
following command to confirm the ip forwarding is on:

# cat /proc/sys/net/ipv4/ip_forward

And I do in fact have a "1" in there.

Did I miss one little step somewhere? I have set these things up
before without issue, so I suspect I am over looking a little step
here.

Ideas?