BotNet News

Your source for Online Security News


A firewall is a device, either hardware or software-based, that monitors traffic and incoming data, verifies access to the network, and decides whether or not to allow or reject traffic based on predefined rules. The firewall acts as a barrier between secured internal networks and untrusted networks such as the Internet.

Different types of firewalls utilize a variety of methods to filter data. Some check the sender’s address, while others examine the contents of the data packet. Next-generation firewalls (NGFs) combine these varied capacities to protect against the full range of threats, from zero day exploits and ransomware to traditional attacks like hacking and phishing.

The earliest iterations of firewalls were developed in the late 1980s and early 90s by multiple researchers at AT&T Bell Labs. Mogul, Reid and Vixie worked on packet filters that helped create the concept of vetting external connections before they could contact hosts in a secure internal network.

Circuit-level gateway firewalls control network traffic at the OSI model’s session layer, instead of the lower packet layers. This type of firewall compares new data packets to the existing connections in its state table. If it matches an established connection, the firewall allows the packet to pass without further inspection. Otherwise, the firewall analyzes the packet based on its own rules for establishing new connections.

Network administrators can manage firewall rules for their multivendor systems using a centralized management tool. This helps to prevent duplicates and redundant elements from slowing down firewall performance. It also helps to improve security by discarding unessential shadowed rules that can cause more critical ones to be neglected.