F is for Firewall
No, not the awful 2006 thriller starring Harrison Ford. In computer lingo, a firewall is a security tool for blocking unauthorized access to a network while still allowing authorized communications. It achieves this with a set of rules for blocking out unwanted transmissions. The name comes from an actual construction term, which meant a wall designed to isolate fire within a building. Despite the vivid image, a firewall can be either hardware or software. Currently, there are four different types of firewall techniques:
- Packet filter: Packet filtering inspects each packet passing through the network and accepts or rejects it based on user-defined rules. Although difficult to configure, it is fairly effective and mostly transparent to its users. It is susceptible to IP spoofing.
- Application gateway: Applies security mechanisms to specific applications, such as FTP and Telnet servers. This is very effective, but can impose a performance degradation.
- Circuit-level gateway: Applies security mechanisms when a TCP or UDP connection is established. Once the connection has been made, packets can flow between the hosts without further checking.
- Proxy server: Intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses.
(List taken from Wikipedia)Although conventional firewalls are common in intranet environments, many personal computers today can benefit from a personal firewall, which controls traffic to and from an individual computer. This is useful for blocking intrusions to that computer, letting the user know when they are connecting remotely to another network, controlling the applications which can access the local network and Internet, and alerting the user when an application attempts to connect to their machine. Personal firewalls are usually in the form of software, and many developers offer their firewalls as freeware. These include:
- Comodo Firewall Pro,
- GhostWall,
- Online Armor Personal Firewall,
- PC Tools Firewall Plus,
- Sygate Personal Firewall,
- Vista Firewall Control, and
- ZoneAlarm.
Make the extra effort to check out one of these options and secure your computer today. A few extra minutes can save a lot of hassle in the future.