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Firewall

Firewall protects networks from threats by filtering out unwelcome data, enforcing policies, and blocking suspicious activity. A firewall can also prioritize bandwidth to mission-critical applications and monitor network health to identify security issues quickly.

Depending on the configuration, a firewall can be positioned at the network perimeter to protect against external threats or embedded inside to prevent internal attacks. Firewall technology comes in a variety of formats, from basic packet filters to advanced next-generation firewall (NGFW) solutions. The process of selecting the right firewall solution requires a comprehensive understanding of business goals, available resources, and IT infrastructure.

The simplest type of firewall filters out unwanted traffic by inspecting each piece of data in a network packet, such as the sender and recipient’s IP addresses and port numbers. A network defender then decides whether the packet should be allowed through based on a set of rules.

A stateful firewall goes a step further by considering the connection states of streams of data, like a bouncer at a nightclub. This type of firewall keeps track of which connections have already been vetted and makes decisions on the basis of that information, rather than looking at each individual data packet.

A combination of packet inspection and TCP handshake verification, stateful firewalls provide more extensive protection than either approach alone. However, this level of contextual awareness may slow down the transfer of legitimate packets compared to other types of firewalls. Gil Shwed and Nir Zuk invented this technology at Check Point in the late 1980s, leading to the first widely-adopted, user-friendly firewall product — 1994’s Firewall-1.