People often ask me about the best way toconfigure their computer to protect against threats, such as worms andTrojan horses. They say they have installed antivirus protection andnever open unexpected email attachments. But they wonder if that isenough. Antivirus protection is certainly an important part of aneffective protection solution. It has the ability to detect knownthreats as well as many new ones via heuristic technologies. But thereis a second technology that can be added to help complete the picture:a firewall.
While antivirus software helps to protect thefile system against unwanted programs, a firewall helps to keepattackers or external threats from getting access to your system in thefirst place. Most people are aware that worms often travel throughemail. They generally arrive as an attachment to an email that the useris enticed to click on by the text of the email itself. We call thesethreats “mass-mailing worms.” The best thing to do with these threatsis simply to delete the email and not click on the attachment.
Other threats travel from computer to computer without the knowledgeof the user. They can find a computer that has lower security settingsor unpatched vulnerabilities, and insert themselves onto that systemwithout the user ever knowing what is happening. Many worms and Trojanhorses, often known as “bots”, travel this way. They utilize theInternet to find computers to infect. The user will never know thattheir system has been compromised because the threat enters theircomputer quietly.
This is exactly where a firewall can help protect you. The firewallmonitors all network traffic and has the ability to identify and blockunwanted traffic. Since most computers these days are connected to theInternet, attackers have many opportunities to find victim computers.These attackers probe other computers on the Internet to determine ifthey are vulnerable to various types of attacks. When they find asuitable computer, they can compromise it and insert themselves ontothat computer. At that point the attacker can make the victim computerperform almost any task he desires. Attackers will often try to stealpersonal information for the purposes of financial fraud. All of thisactivity takes place in the background without the user knowing what ishappening.
There are two basic types of firewalls: client firewalls andappliance firewalls. A client firewall is software that resides on thecomputer itself and monitors all of the network traffic on thatcomputer. An appliance firewall is a hardware device that is connectedbetween the Internet and your computer. These devices are often used insmall network environments where several computers need to share thesame Internet connection. The small routers that many people use intheir offices and homes usually have built-in firewalls. If you use arouter, make sure it has a firewall. Both types of firewalls can keepthe attackers from gaining unwanted access to your computer. Users whotravel should always have a client firewall installed on their system.You don’t want to take any chances when you are connected to theInternet away from the office or home.
While antivirus software is a great tool to help keep you safe,adding a firewall will give the bad guys out there the one-two punchthat will be a knockout.