Dustin Krysak wrote: > 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 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. sounds like you're trying to do a 'NAT' (network address translation) network, where you're local network is on private IP space (192.168.x.y or 10.x.x.x or whatever), and you're sharing a single public IP. this requires several very specific and moderately complex rules to implement what Linux calls 'MASQUERADE', and you need to load the ip_conntrack module into the kernel, and probably a few more. at a BARE minimum, you need some variant on these two rules... iptables --table nat --append POSTROUTING --out-interface $WAN -j MASQUERADE iptables --append FORWARD --in-interface $LAN -j ACCEPT (where $WAN, $LAN are eth0, eth1, or whatever your internet and local interfaces are) if you google for: LINUX MASQUERADE, you'll find all sorts of confusing info on this :)