Smoothwall may not be forwarding port 80

I'd suggest a systematic approach. The nmap result and the "Gateway Timeout" error suggest IMHO that either some router on your LAN is dropping the packets, or that the forwarding does not work correctly.

1. Check on which interfaces it's listening (netstat -ntl) to make sure it's accessible on the public interface.
2. Check the actual packet filter configuration (iptables -nL, iptables -t nat -nL, iptables -t mangle -nL) to make sure that it's really not the packet filter on the host itself. Keep the default policies in mind!
3. Make a portscan from a host on the same network segment to check whether access from some other host is possible at all.
4. Check the configuration of any router/firewall between the web server and your border router.
5. Check the router/firewall configuration (port forwarding as well as filtering rules).
6. Check your private DNS config. Maybe it's an internal name resolution issue.

I'd suspect that you made some mistake there, because ethereal should at least show the outgoing packets, even if there are no replies.

cu

If you're getting an HTTP status messages, it would seem that you're reaching the web server. Are your browser or firewall configured to use a proxy server, perchance?

-Gary

The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the URI (e.g. HTTP, FTP, LDAP) or some other auxiliary server (e.g. DNS) it needed to access in attempting to complete the request.

Note: Note to implementors: some deployed proxies are known to return 400 or 500 when DNS lookups time out.

Thanks for your responses. I've fixed the problem. The ADSL router needs port forwarding enabled too. Did this and up popped the website. Lovely!