Basics in Iptables and Firewalld
Managing network traffic is one of the toughest jobs system administrators have to deal with. He must configure the firewall in such a way that it will meet the system and users requirements for both incoming and outgoing connections, without leaving the system vulnerable to attacks. This is where iptables come in handy. Iptables is a Linux command line firewall that allows system administrators to manage incoming and outgoing traffic via a set of configurable table rules.