What is a Firewall?
Firewall is a special type of network security device or software program that monitors incoming and outgoing data traffic and permits or blocks information based on pre-defined set of rules. It acts as a barrier between an internal private network and untrusted external networks like the Internet to prevent malware infections and viruses from entering the network.
Originally, the first firewalls were physical hardware devices that plugged into a computer network. Then the firewall technology developed to where it could be deployed as a software program on computers or in the cloud. Today, firewalls are a combination of hardware and software or can be a virtual device that is run on a cloud service.
The basic function of a firewall is to filter data attempting to enter the network by checking for things such as if the incoming information is harmful and the sender’s IP address. It then opens or closes the network gate accordingly. Firewalls can also perform application layer inspection, which is more sophisticated than packet filtering.
Think of a bouncer at a bar who checks ID to make sure people are not underage or armed before they get into the club. A proxy firewall does a similar job by intercepting and inspecting outgoing information on behalf of the client. When the firewall receives the response from the server, it creates a new connection with the client. Thus, the proxy firewall keeps a separation between the server and the client and protects the privacy of the client.