Nftables is a programmable packet filter for Linux in which the matching mechanism is implemented as virtual-machine subprograms compiled to pseudocode while the rule management tool is in use. It is a high-performance and highly flexible apparatus integrated with the Netfilter subsystem, useful not only for building firewalls, but also for translating addresses, classifying, counting, and routing traffic. Writing rules bears some resemblance to event-driven programming.