The Linux iptables tool is extremely useful for setting up firewalls, configuring NAT, performing port forwarding, and logging low-level network access. Frequently, two or more of these features are performed together, such as firewalling a NAT router and logging at least some failed access attempts. A single iptables command sets up a single rule, but most tasks you perform with this tool require multiple rules. Therefore, chances are you'll set up an iptables firewall script that includes many iptables commands.