What command is used to create firewall rules on a Linux system?

Iptables is traditionally the command-line utility used to configure and manage the Netfilter firewall on Linux systems. It allows users to set up rules that control the incoming and outgoing traffic, helping to protect the system from unwanted access. With iptables, administrators can specify which network traffic is allowed or rejected based on various criteria such as IP addresses, port numbers, and protocols.

While firewalld and nftables are also tools used for managing firewall rules, they can be seen as newer alternatives or enhancements over iptables. Firewalld provides a higher-level management interface that can simplify the use of iptables with zone-based configurations and dynamic rules, while nftables is a more modern replacement that consolidates and improves upon the functionality of iptables. The 'tc' command, on the other hand, is used for traffic control, specifically for managing bandwidth, queuing disciplines, and traffic shaping, rather than creating firewall rules.

In summary, iptables is the right choice for creating firewall rules due to its long-standing presence in Linux systems as the go-to utility for direct rule management.