What is Firewall ?

Firewall are hardware and software combinations that are built using routers, servers and variety of software. They sit at the most vulnerable point between a corporate network and the Internet and they can be as simple or complex as system administrators want to built them. Firewalls reduce the speed of access of networks.

Router or remote-access server (or several routers or access servers) designated as a buffer between connected networks. A firewall uses access lists and other methods to ensure the security that enforces a boundary between two or more networks.

A firewall can either be software-based or hardware-based and is used to help keep a network secure. Its primary objective is to control the incoming and outgoing network traffic by analyzing the data packets and determining whether it should be allowed through or not, based on a predetermined rule set. A network's firewall builds a bridge between an internal network that is assumed to be secure and trusted, and another network, usually an external (inter)network, such as the Internet, that is not assumed to be secure and trusted.

Many personal computer operating systems include software-based firewalls to protect against threats from the public Internet. Many routers that pass data between networks contain firewall components and, conversely, many firewalls can perform basic routing functions

Every time a corporation connects its internal computer network or LAN to the Internet, it faces potential danger regarding security. Due to the Internet's openness, every corporate network connected to it is vulnerable to attack. Crackers on the Internet could break into the corporate network and do harm in a number of ways. Some such methods are the  following:

a. They could copy or damage important data.
b. Damage individual computer data or the entire networking.
c. Use the corporate computer's resources or use the corporate network and resources as a way of posing to be a corporate employee.

The solution for all these problems and many more is to built 'firewalls' to protect its network. These firewalls allow anyone on the corporate network to access the Internet, but they stop crackers, hackers or others bent on to do mischief on the Internet from gaining access to the corporate network and causing damage.

Benefits of using a Firewall

i. Protection from services which are inherently more prone to attacks.
ii. Access to host in the network can be strictly controlled.
iii. Security is concentrated on a single firewall system. This leads to better implementation of authentication procedures.
iv. Logging and statistics of network use and misuse.
v. Policy enforcement.