I recently installed Red Hat 8.0 in my system and during the installation I chose the firewall setting to High, didn't check the eth0 (I use ethernet to access internet and network) as trusted. Now I'm having problem connecting to network or the internet. The device is working fine. So I tried to lower the security level from Security Level Configuration panel from high to medium, selected eth0 as trusted and checked DCPH for incoming messages. But everytime I click OK, the changes don't seem to take effect cause the next time I open this Configuration panel, the level is High and none of the things I selected before seem to be selected. I don't know if this is the real problem for my connection not working. If it is, there should be some manual(command level) way to change the Security Level rather than windows-styled click system. Please, I need your help and would highly appreciate it.

Please read this (end of a) discussion about RH8's firewall: http://www.linuxquestions.org/questi...353#post172353 this thread http://www.linuxquestions.org/questi...threadid=35559 and when you're ready to build it yourself, search LQ for scripts and/or visit some links like:

Netfilter+Iptables HOWTO:
LQ search: iptables+howto,
Linuxguruz.org,
Netfilter.org Packetfiltering HOWTO,
Linuxsecurity.com Iptables tutorial,
Andreasson's Iptables tutorial,
Iptables Connection tracking.

Other resources/misc stuff:
Assigned ports > 1024,
Port designations,
FAQ: Firewall Forensics (What am I seeing?),
Linux Firewall and Security Site,
Auditing Your Firewall Setup (old, still usefull),
Netfilter Iptabes/Ipchains Log Format.

I can give a simple script to flush the firewall

the link above are very usefull for you to make your own firewall


#!/bin/bash
### Reset FW ####

iptables -F
iptables -F -t nat
echo 0 > /proc/sys/net/ipv4/ip_forward

### Politici de FW ###

iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT