When people start working with Debian or Linux servers in general, they often hear the word firewall very quickly. A firewall is one of the most important security layers on a system. It controls which network traffic is allowed in or out, and it helps protect services such as SSH, web servers, mail servers, or databases from unwanted access.
On Debian, there is not just one single firewall solution. There are several different tools and frameworks, and beginners are often confused because they see names like iptables, nftables, ufw, or firewalld. They all relate to firewall management, but they work in different ways and are aimed at different use cases.
The classic firewall system on Linux for many years was iptables. It allowed administrators to create detailed packet filtering rules for incoming, outgoing, and forwarded traffic. With iptables, you can block ports, allow only certain IP addresses, or define more advanced filtering logic. It is powerful, but many users find it diff…login to view the rest of this post