What is Linux Netfilter? Netfilter is a framework provided by the Linux kernel that allows various networking-related operations to be implemented in the form of customized handlers.
What is difference between iptables and Netfilter? There may be some confusion about the difference between Netfilter and iptables. Netfilter is an infrastructure; it is the basic API that the Linux 2.4 kernel offers for applications that want to view and manipulate network packets. Iptables is an interface that uses Netfilter to classify and act on packets.
What is hook in Netfilter? The Netfilter framework provides a series of “hooks” inside the Linux kernel network stack that are traversed by network packets (Figure 1). Other kernel components can register callback functions with those hooks, enabling them to inspect any packets coming in and decide whether to drop or accept them.
How does Firewall work in Linux? Firewalls create a barrier between a trusted network (like an office network) and an untrusted one (like the internet). Firewalls work by defining rules that govern which traffic is allowed, and which is blocked. The utility firewall developed for Linux systems is iptables.