A firewall is a network security device that monitors incoming and outgoing network traffic. A firewall filters this traffic and blocks outsiders from gaining unauthorized access to the private data on your computer.
A firewall only allows configured incoming connection requests. It also only permits IP addresses coming from authorized sources.
Firewalls protect traffic at a computer’s
For example: “Source address 172.18.1.1 is allowed to communicate with destination 172.18.3.1 through port 40."
Based on their overall structure and mode of operation, firewalls can be classified into numerous categories.
There are three major firewall types:
Packet-filtering firewalls act as a checkpoint at a traffic router that inspects IP addresses, packet type, and port numbers in data packets coming through the router.
The packet itself is not checked by these firewalls. So if a packet has malware, but also has the correct TCP handshake, it would be allowed to pass.
Proxy firewalls filter incoming traffic between the network and the traffic source at the application layer.
After inspection, these allow the packet to connect to the destination.
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