What is the difference between a firewall and iptables?

Firewall is a general term that refers to a network security system that controls incoming and outgoing traffic based on predefined rules. It can be hardware or software-based.

iptables is a command-line utility in Linux OS used for configuring packet filtering (firewall) in the Linux kernel (Netfilter). In other words, iptables is one of the software tools for implementing firewall functionality.

Main differences:

• Level of abstraction: Firewall is a concept or device/software type, iptables is a specific tool for managing firewalls in Linux.
• Platform: Firewalls can be implemented on various platforms (hardware, software OS), iptables is specific to Linux.
• Implementation: iptables interacts directly with the Netfilter framework in the Linux kernel to apply filtering rules. Other firewalls may use different mechanisms.
• Management interface: Firewalls can have various interfaces (GUI, CLI), iptables is primarily managed via CLI.

Thus, iptables is a tool for configuring firewalls in Linux, and a firewall is a general term for a system that performs traffic filtering functions.

Example of an iptables command:

// Add rule: allow incoming SSH on port 22
iptables -A INPUT -p tcp --dport 22 -j ACCEPT