ADSL Firewall not passing Web protocol

I am trying to set up a Linux firewall with an ADSL Router modem on a
LAN network. The Router plugs into the hub and has a fixed address of
192.168.1.1. The firewall has been assigned an address of
192.168.1.254. It comes frustratingly close to working. Telnet and
Kazaa (oddly enough) work from my Windows machines, but not ordinary
web browsing, AOL Messenger, or even pinging an internet site. I tried
to start with a very basic and open iptables configuration:

iptables -F
iptables -X
iptables -P OUTPUT ACCEPT
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
modprobe iptable_nat
iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to-source
192.168.1.254
echo 1 > /proc/sys/net/ipv4/ip_forward

If I save it, I get the following in /etc/sysconfig/iptables:

# Generated by iptables-save v1.2.7a on Sat Dec 20 23:22:01 2003
*filter
:INPUT ACCEPT [140:8022]
:FORWARD ACCEPT [5:304]
:OUTPUT ACCEPT [102:7149]
COMMIT
# Completed on Sat Dec 20 23:22:01 2003
# Generated by iptables-save v1.2.7a on Sat Dec 20 23:22:01 2003
*mangle
:PREROUTING ACCEPT [220:12352]
:INPUT ACCEPT [4915:455040]
:FORWARD ACCEPT [7175:5012998]
:OUTPUT ACCEPT [164:12551]
:POSTROUTING ACCEPT [10990:5466666]
COMMIT
# Completed on Sat Dec 20 23:22:01 2003
# Generated by iptables-save v1.2.7a on Sat Dec 20 23:22:01 2003
*nat
:PREROUTING ACCEPT [1:576]
:POSTROUTING ACCEPT [1:84]
:OUTPUT ACCEPT [2:168]
[1:84] -A POSTROUTING -o eth0 -j SNAT --to-source 192.168.1.254
COMMIT

Can anyone suggest what I might be missing? Thanks for any help.

--Dave

(E-Mail Removed) (Dave Stauffer) écrivait
news:(E-Mail Removed) om:
> 192.168.1.1. The firewall has been assigned an address of
> 192.168.1.254. It comes frustratingly close to working. Telnet and

The firewall should also have a public ip address, when the line is up,
certainaly on a ppp interface (not in 192.168.x.x or 10.x.x.x range).

> iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to-source
> 192.168.1.254

and so you shoudl use the public interface and adress in the firewall
rules :

iptables -t nat -A POSTROUTING -o ppp+ -j SNAT --to-source <public_ip>

or masquerade (especially if you have a dynamic address) :

iptables -t nat -A POSTROUTING -o ppp+ -j MASQUERADE


Marquerading get the current interface ip adress, and reset lost
connexion if the ip change.


Regards