An application firewall is a feature that is designed to filter access to a computer or network. Used in computer security, a firewall can be either hardware or software, and is sometimes a combination of the two. Application firewalls are software programs that identify and control the source of requests to and from an application or computer service. Most often used to protect users from Internet threats, web application firewall programs can also be used to help prevent attacks from hackers. Examples of application firewall programs include AppArmor® by Novell®, Netscaler® by Citrix® and dotDefender® by Applicure Technologies®.
An important part of computer security, an application firewall protects a computer by combating the vulnerabilities of an application. If the security of an application is left unchecked, software weaknesses and malicious programming code could allow hackers to gain access to computer files or cause damage to the computer. Application security is a field of work that focuses on designing and maintaining software programs to prevent and solve security problems in a computer program.
Though application firewalls can keep malicious software and computer intruders at bay, their use can also conflict with software programs running legitimately on a computer. To eliminate software conflicts with a firewall, many application firewall programs have settings that allow approved computer programs to bypass the firewall. When an application firewall does not have bypass settings, it may be necessary to shut down the program running the firewall to successfully run the conflicting software program. The firewall can be restarted after the conflicting program is closed.
When the function of an application firewall focuses on requests going to and coming from the Internet, they are called web application firewalls (WAF). One responsibility of an application firewall is to protect a computer from malicious requests by identifying dangerous Internet requests and bad data sources. A firewall can also protect an application from acquiring or executing password or Trojan-horse attacks from hackers.
Generally, application firewalls are designed to protect one program or set of programs from tampering, and they do not offer a complete Internet security package. For extra security, application firewalls are often used in combination with an antivirus program and a proxy server. A proxy server is a hardware device or software program that intercepts requests sent to and from another computer over a network or the Internet. Using a proxy server can help protect an Internet user's anonymity by providing information about the proxy server in lieu of user information.