Iptables is a command-line firewall tool that allows or blocks traffic using policy chains. When a connection attempts to establish itself on your system, iptables searches its rule list for a match. If it cannot discover one, it falls back on the default action. iptables is nearly usually included with each Linux distribution. Iptables tends to use 3 different chains: input, forward, and output. With this, you can create different rulesets for different machines on the network, however, why not make it easier by using firewall-cmd!