Locking Down Your Firewall Modify your firewall script...

• To backup and then edit your current firewall script /etc/init.d/firewall.rules :

• # cp -a /etc/init.d/firewall.rules /etc/init.d/firewall.rules-BAK # vim /etc/init.d/firewall.rules

• To shut off external ICMP packer replies:

  • ... # Allow Ping and friends. ## TWW: but drop all ext. pings Bv> ${IPTABLES} -A INPUT -p icmp -i ${OUT_DEV} -j DROP ${IPTABLES} -A INPUT -p icmp -j ACCEPT ${IPTABLES} -A OUTPUT -p icmp -j ACCEPT ...

• To test it: # etc/init.d/firewall start

• To Save it (make it persistent across reboots): # save-config

• Read through the rest of your firewall script and examine its flow from top to bottom.

Notes: