Types of Firewalls
Firewall is a network security device that monitors and regulates outgoing data traffic based on a set of pre-programmed rules. It creates a barrier between a secured internal network and outside untrusted networks like the Internet to prevent cyberattacks that expose users to phishing, identity theft and online fraud. Firewalls can either be software based or hardware devices.
Packet filtering firewalls analyze outgoing data packets and distribute them based on the filters’ standards such as source, destination and application protocols. They’re a cheap and quick way to control network access. For small or budget-constrained businesses, this type of firewall is a solid choice.
Proxy services are network security systems that secure a client’s networks while filtering messages at the application layer. These are a more advanced version of a packet filtering firewall and can be configured to ‘accept’,’reject’ or ‘drop’ specific data packets.
Circuit-level gateway firewalls operate at the OSI network level (layer 3) and filter outgoing data by checking TCP handshake packets between two hosts. This ensures that a host is who they claim to be, preventing two networks from directly connecting without permission.
Stateful inspection firewalls, also known as dynamic packet filtering, allow or reject connections based on a state table that keeps track of each active connection. This allows them to learn from past interactions with certain types of traffic and automatically vet future requests instead of repeatedly reapproving connections. Next generation firewalls, or NGFW, integrate the capabilities of each of these individual firewall types. They also incorporate additional security devices such as anti-virus, anti-malware and Intrusion Prevention System.