What is a Firewall?
To enable you to get a quick understanding of what a Firewall is – imagine a medieval castle where to fortify the castle, the ruler would have a deep moat dug all around, and a drawbridge constructed as a single point of entry and exit. The drawbridge would have a tight security to screen off unwanted entry and exit. Also, when the castle was attacked by enemies, the drawbridge was withdrawn, cutting off all intrusions. With this arrangement, rulers in the olden days were able to keep their castle well protected.
An Internet firewall can be perceived as an electronic drawbridge and works on exactly the same philosophy. An organization’s network is setup in a manner so that there is a single point of entry and exit to the Internet. A firewall, which is essentially a set of hardware devices and software, is then placed at the entry point of the organization's private network and works to screen off all unwanted access both-ways. All communication data packets from any computer inside the private network to the outside world will be routed through the firewall. Also, all data packets from any computer in the outside world to any computer within the private network will always be routed through the firewall. The organization would implement a strict policy not to permit anyone to connect through any other means that may bypass this arrangement, such as a direct dial-up wireless modem. Thus the organization will need to focus only on fortifying the firewall, which will singly control access between the two networks.
Few businesses would choose to operate without a series of locks, alarms and security cameras to protect their premises and inventory from intrusions and theft. Protecting your computer systems is equally important, to prevent malicious users from disrupting your operations or -- even worse -- stealing your private data or intellectual property.
One of the key tools used for computer security is a Firewall, and no company can afford to operate without one.
Firewall Basics
No single product or service will provide you with complete security, but a firewall is one of the cornerstones of any network security strategy. Think of it as the electronic equivalent of the sentry at the drawbridge. It inspects all the data passing in or out of the network, ensuring that the traffic is legitimate. When properly configured, a firewall should allow your users access to all the resources they need while still keeping out any malicious users or programs.
Hardware Firewalls:
One way to provide firewall protection is through a separate piece of hardware that's placed between the network or user and any outside networks such as the Internet. Hardware firewalls have several advantages. They use their own preinstalled software and operating system, so malware based on an OS such as Windows can't attack them. One hardware firewall can protect every device on the network, without the time and trouble of configuring them individually. That's also a benefit when you need to upgrade, since updating one firewall is faster and easier than updating a room full of computers. Many of your existing network routers probably have firewall functions built in, if you choose to use them.
Software Firewalls:
Firewall software on your network servers or individual computers provide an extra level of security, and they're often used in conjunction with hardware firewalls. They enable users with different needs to customize their own levels of protection, including the ability to allow individual programs access to the Internet -- or not -- on a case-by-case basis. Alternatively, your network administrator can set up firewall permissions for individual users or groups of users. That strategy can be used to block or control employees' access to external websites, either in the interest of productivity or to prevent employees from using company resources for illegal or unapproved purposes.
Firewalls aren't meant to be used alone because they are largely ineffective against malware from spam emails, phishing scams and website links. They should be used as one defensive component in a system that includes anti-virus, anti-spyware and anti-spam protection.
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