It is software or hardware that blocks incoming or outgoing traffic from the internet to your computer. They are responsible for securing a network.
The figure above shows how good traffic is allowed to enter the user’s network. Similarly, the figure below shows how the firewall blocks the bad traffic, thereby protecting the user’s network.
A few common types of Firewalls
- Packet-filtering Firewalls: These are the most common type of firewalls that analyze packets and let them pass through only if they match an established security rule-set.
- Proxy Firewalls: They filter network traffic at the application level.
- Stateful Multilayer Inspection (SMLI) Firewalls: These filter packets at the network, transport, and application layers. Here, the packets are compared to the known trusted packets.