iptables
![Packet flow paths. Packets start at a given box and will flow along a certain path, depending on the circumstances.](/Images/godic/202501/21/Netfilter-packet-flow.svg2338.png")
iptables is a user-space application program that allows a system administrator to configure the tables provided by the Linux kernel firewall (implemented as different Netfilter modules) and the chains and rules it stores. Different kernel modules and programs are currently used for different protocols; iptables applies to IPv4, ip6tables to IPv6, arptables to ARP, and ebtables to Ethernet frames.