To create basic iptables firewall in a Redhat compatible distro, edit the /etc/sysconfig/iptables file and add the info below: *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -m state --state INVALID -j DROP -A INPUT -i lo -j ACCEPT -A INPUT -s 192.168.0.50 -p udp -m udp --dport 123 -j ACCEPT ..