What is a Firewall?
A firewall is a computer network security system that restricts internet traffic in to, out of, or within a private network. A firewall is either software or a dedicated hardware-software unit that functions by selectively blocking or allowing data packets to pass. It acts as an extra layer of security and is a critical component to help prevent malware activity, and to protect anyone from the outside world who might be trying to spy on your personal information or steal your work.
Connecting a personal computer to a corporate network or the internet opens up a wealth of benefits, from easier collaboration and resource sharing to improved creativity. However, connecting a device to an open network also creates numerous risks, from cyber trespassing and unauthorized intrusion by hackers looking for malicious data to theft of personal or financial information.
Firewalls are designed to keep out unwanted incoming or outgoing data by filtering it based on the source and destination IP addresses, and the communication ports of each packet. This allows the firewall to detect patterns and anomalies, and to identify potential threats that may be attempting to infiltrate a system.
The most advanced firewalls operate on a higher level of the OSI network protocol stack, and can identify specific application signatures, such as Instant Messenger (IM) and peer-to-peer file sharing programs that are largely considered malware. This level of security identifies and manages threats from both the data layer and application layer simultaneously, which is more effective than only managing the threat at one level at a time. The firewall can then accept, reject or drop this traffic as necessary. The invention of the stateful inspection firewall by Gil Shwed and Nir Zuk at Check Point in 1993 led to the first popular and user-friendly firewall product, branded as Firewall-1, which was released in 1994.