What is it? iptables is a cli frontend to netfilter, the Linux kernel firewall/nat implementation for OSI layer 3 and 4.
Don't use iptables to apply your rules one at a time, use iptables-restore to apply a whole ruleset in one action. Set your INPUT and FORWARD policy to DROP. Don't set your OUTPUT policy to DROP unless you really know what you're doing. If you're going to implement a blacklist or whitelist, you should look […]