>how could i add / remove iptable rules on cet os 5.4 final for tcp / udp base on ports Wow Cahit, you are a sucker for punishment buddy:) First, post in text, then do a smidge of reading first... `man iptables` or google? I am guessing your iptables are stock as install left them? You might try `system-config-security-level-tui` which can actually be scripted, or you can issue low level commands like: iptables -I RH-Firewall-1-INPUT -m state --state NEW -m multiport -p tcp -s 10.0.0.0/24 -d 10.0.0.0/24 --dports xxx,yyy,zzz -j ACCEPT etc etc etc