Firewall a pristine Ubuntu 8.04 box
Follow these simple instructions to block all traffic but SSH to your box. Once you have these rules running you can punch more holes as required.
sudo apt-get install iptables
sudo iptables -A INPUT -i lo -j ACCEPT
sudo iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
sudo iptables -A INPUT -p tcp --dport ssh -j ACCEPT
sudo iptables -A INPUT -j DROP
sudo sh -c "iptables-save -c > /etc/iptables.rules"
If you'd like to save your current rules when you stop - or load the rules when you start the box, change your /etc/network/interfaces
file so that it contains pre-up and post-down hooks to load / save the rules.
pre-up iptables-restore < /etc/iptables.rules
post-down iptables-save -c > /etc/iptables.rules
If you're hosted at Xeriom Networks and would like to be monitored by the monitoring service there, allow ICMP Type 8 from monitor.xeriom.net
.
sudo iptables -I INPUT 4 -s 193.219.108.245 -p icmp -m icmp --icmp-type 8 -j ACCEPT
Remember to save the new rules to the iptables.rules
.
sudo sh -c "iptables-save -c > /etc/iptables.rules"
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If you'd like to have a conversation about this post, email craig@barkingiguana.com. I don't bite.