Firewall (computing)

A firewall is a special tool used in computing to keep information safe. It works like a guard that watches all the data moving in and out of a computer or a group of computers. This data is called network traffic. The firewall checks each piece of traffic against a set of rules to decide if it is allowed to pass through or if it should be blocked.

Firewalls are very important because they create a barrier between places that are trusted, like a school’s computers, and places that are not trusted, such as the Internet. This helps stop harmful things from getting into the trusted area. Firewalls can be set up in two main ways: one that protects an entire network of computers, and another that protects just a single computer. Both types work to make sure only safe and needed information can move between different areas.

History

The word firewall started as a term for a wall that stops a fire from spreading between buildings. Later, it was used for things like the metal sheet that separates the engine part of a vehicle or aircraft from the passengers.

In the 1980s, when the Internet was still new, the word "firewall" began to be used for network technology. Before firewalls, routers were used to help keep networks separate.

The idea appeared even earlier in a 1983 movie called WarGames.

One of the first successful firewall products was called the PIX Firewall. It was created in 1994 by a small company. This product helped people connect their private networks to the public Internet safely. It became very popular and won an award in 1995. Later, a bigger company bought the rights to this technology.

Types of firewalls

See also: Computer security

Firewalls come in two main types: network-based and host-based. Network-based firewalls sit between different networks, like between your home network and the internet, controlling how information moves between them. They can be software, special hardware, or even virtual systems. Host-based firewalls are placed directly on a single computer to manage its connections and resources.

The first type of firewall, called a packet filter, checks small pieces of information called packets as they move between computers. It decides what to do with each packet based on simple rules, like where it comes from or where it's going. Later, more advanced firewalls learned to remember conversations between computers, helping them spot unusual activity. Today, some firewalls can understand specific applications, like web browsing or file sharing, offering even better protection by checking more details of each connection.

Firewall Policies

At the heart of a firewall are rules that decide what internet traffic is allowed or blocked. These rules check details of each piece of data, called a packet, to decide if it can pass through. Important details include where the traffic comes from, where it is going, which specific online service it uses, and what kind of network communication it is.

Networks can be divided into zones, like a safe area and a less safe area, to control traffic between them. For example, a school might allow students to visit websites but block them from accessing certain services. Firewalls can also use user names instead of just computer addresses to apply rules, making it easier to manage who can see what on the network. This helps keep the network secure by letting administrators control access based on who the user is, not just where they are connecting from.

Configuration

Setting up a firewall can be tricky and sometimes leads to security problems if not done correctly. Firewalls are adjusted based on the kind of network, like public places or private homes. People in charge make rules to decide which information can come in or go out, helping to keep networks safe from unwanted visitors or harmful software.