WHAT IS FIREWALL

What is a firewall?

A firewall is a software program or piece of hardware that helps screen out hackers, viruses, and worms that try to reach your computer over the Internet. If you can’t start Windows Firewall or you are getting an error, use our free tool to diagnose and fix problem

A firewall is a network security device that grants or rejects network access to traffic flows between an untrusted zone (e.g., the Internet) and a trusted zone (e.g., a private or corporate network). The firewall acts as the demarcation point or “traffic cop” in the network, as all communication should flow through it and it is where traffic is granted or rejected access. Firewalls enforce access controls through a positive control model, which states that only traffic defined in the firewall policy is allowed onto the network; all other traffic is denied (known as “default deny”).

There are basically two types of Firewalls. They are software and hardware Firewall. A firewall is a software or hardware that filters all network traffic between your computer, home network, or company network and the internet.

A firewall is a network security system, either hardware- or software-based, that controls incoming and outgoing network traffic based on a set of rules.Acting as a barrier between a trusted network and other untrusted networks -- such as the Internet -- or less-trusted networks -- such as a retail merchant's network outside of a cardholder data environment -- a firewall controls access to the resources of a network through a positive control model. This means that the only traffic allowed onto the network defined in the firewall policy is; all other traffic is denied.

A firewall is a boundary or a wall to keep intruders from attacking the network. The firewall is network device that is in between a private network and the internet. The firewall is configured to inspect network traffic that passes between the network and the internet. We can assign rules or protocols to the firewall to allow data to be shared. If the protocol isn't included in the approved list it would destroy or discard the packet of data and deny it from entering the network.

History of Firewall

Computer security borrowed the term firewall from firefighting and fire prevention, where a firewall is a barrier established to prevent the spread of fire

Advantages And Disadvantages Of Firewalls

ADVANTAGES

A firewall blocks "evil packets" from being "permitted to reach a place where they can do harm," says Terry Gray, Chief Technology Architect for the University of Washington. The key issue is not whether to block harmful packets, but where to block them. The individual system's operating system-based firewall can be configured to provide a great deal of security, but a network-based firewall, such as a router, can protect multiple systems simultaneously.

DISADVANTAGES

Packet filtering by a software firewall can degrade your system's performance, because it's a demanding task to examine every packet of data. A hardware firewall eases this burden. Whichever option you choose, configuring and maintaining the firewall can be a difficult maintenance chore. A network firewall also can lend users a false sense of security, encouraging them not to maintain security at the machine level. If the network firewall fails or is not configured properly, this could prove disastrous.

There are mainly two types of firewalls.
Software firewalls and hardware firewalls

Disadvantages of using firewalls based on packet filtering

Packet filters do not understand application layer protocols.

Packet filters does not offer any value-added features, such as HTTP object caching, URL filtering,
 and authentication because they do not understand the protocols being used.

Packet filtering routers are not very secure.

Can't discriminate between good and bad packet

New rules may be needed to be added if an employee needs special requirements to connect to the internet.

Difficulty of setting up packet filtering rules to the router

There isn't any sort of user based Authentication.

Packet filter cannot authenticate information coming from a specific user.