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What is a Firewall?

Exactly what is a firewall? Well, finally, the boys in the tech department are getting a little descriptive with their terminology. Like a lot of terms in technology, the name “firewall” comes from an unusual source. The term first became used when houses were constructed with bricks between the walls. Of course, this would prevent the spread of fire. This is a perfect analogy, since a modern firewall does the same thing - separate one zone from another for the sake of safety.

Imagine we have two zones; public and private. The private zone is everything in your home network. This could be a network of computers, peripheral devices such as printers, routers, and anything else that may be influenced by or communicate with the internet. Naturally, this is a very safe environment - and it’s doubtful and harm could come to the network, without influence of a public network. The public network is everything else that your private network might communicate with via the internet.

Think of a firewall as a junction between the two zones - something that filters out “bad” traffic to prevent harm to the private network. This bad traffic can be anything from a virus, attack from malicious hackers, or anything else that would compromise the security, or even do damage to a private network. Just like the bricks in the wall, we want to repel anything that can do harm - not a bad analogy at all!

Do I Need a Firewall?
Contrary to mainstream belief, firewalls are available through both hardware and software - although you are probably familiar with the software types. Oddly enough, it is more than likely you have a hardware firewall and don’t even know it! Routers have been increasingly tight in security, and include their own firewalls to help protect networks. If you have a network of computers, or even in some cases certain types of high-speed internet, you may already have a firewall. This doesn’t mean that a software firewall isn’t needed, however, as a combination of the two is even better.

Keep in mind that a firewall isn’t an all-in-one security package. The most common forms of attack firewalls protect from are: backdoors from applications and operating systems, remote logins, destruction of key files or even an entire hard drive, viruses, spam, and e-mail bombs. Don’t fret if you don’t know what some of these terms are - just know that firewalls essentially protect a home user from giving control of their computer to a malicious hacker.

Dumpster diving may not be vogue, but it certainly has proved that firewalls can’t protect against everything. That’s right - digging through a dumpster can let hackers with malicious intent into a private network. In 1999, a group by the name of Phonemasters penetrated security at large corporations and conglomerates. Not through technology, but through merely digging through trash and finding valuable information. AT&T, Sprint, MCI, WorldCom, and many other businesses experienced major security breaches due to this basic form of hacking.

In short, a firewall is needed if any type of network is to be protected from a public network. Keep in mind that firewalls aren’t the final solution in security - unconventional methods such as dumpster diving and social engineering have made security a bit more complex. Techniques such as IP spoofing have also made firewalls ineffective in some cases - we’ll take a closer look at that in the next section.

Alright, Talk Nerdy to Me!
Enough about theory, let’s get down and dirty to the specifics of firewall operation. There are four main types of protection firewalls offer.

Packet Filtering
Packet filtering is the process of a firewall examining incoming packets of information - and verifying that the sender is a trusted source. For instance, a packet of information from Microsoft will undoubtedly be trusted. The same packet of information from a suspicious internet website might be blocked, because of the IP address. An IP address is a number assigned to computers and devices, and each one must be unique. Because of this, we can actively select which IP addresses are most likely good, and which ones aren’t.

Don’t be so sure that this is a fail-proof method just yet. IP spoofing is the process used to make an IP address look like it is coming from a different computer or device. In our example above, the suspicious website might use IP spoofing to make the firewall think the information is actually coming from Microsoft. Of course, newer firewall techniques help prevent against this. Not to mention it’s very unlikely you’ll ever encounter IP spoofing anytime soon, unless you run a large business that is worth the effort in hacking.

Application and Circuit-Level Gateways
Gateways control flow of packets of information. An application gateway outlines the specific guidelines that any one application can follow. A File Transfer Protocol program, known as FTP, is a way to send a receive files quick and painless. They pose security risks, however, and we can use an application gateway to tell the program what it can and can’t send information to.

A circuit level gateway is similar, but operates differently. Once any type of TCP or UDP connection is established, security checks are made only once. Afterwards, no security checks are made for the remainder of the session. (TCP and UDP are both ways of exchanging information between two computers, which of course has potential for security risks.)

Proxy Server
A proxy server, as most have come to know it, is a way to access MySpace or Facebook at work and school. Much like these internet proxies work, a firewall proxy will enable a computer to spoof its actual identity. Hiding the network address of a private network ensures that hackers will have a much harder time to cause trouble or destruction - because they’ll have to find your network first!

Wrapping It Up
Firewalls have become increasingly complex in how they operate, to keep up with the also increasing technologies hackers are acquiring (Or lack thereof). Home users will more than likely need to shop around for a software firewall, if access to the internet or an unsecured private network is present. Corporations will obviously need them without a doubt - and a good paper shredder for all the more basic forms of hacking a network.

They might not protect houses anymore, but the right firewall can still ensure multi-thousand dollar computers and devices don’t get harmed. And, word to the wise, leave the Windows Firewall behind. And be sure to read our article on the best firewalls to date, for the best protection against harm!

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