Computer Firewall: Definition: A Computer Firewall is a shield that protects your computer system by creating a barrier between your computer, or internal (inside) network, and the outside world. Computer Firewall filters traffic into and out of the firewall is blocked or restricted as you decide. By blocking all unwanted traffic with the Computer Firewall and restricting other traffic to those protocols or individuals that need it you can greatly improve the security of your internal network.
There are several types of firewall techniques:
Packet filter: Looks at each packet entering or leaving the network and accepts or rejects it based on user-defined rules. Packet filtering is fairly effective and transparent to users, but it is difficult to configure. In addition, 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.
Purpose of a Firewall
Detects and blocks all intrusions by hackers
Blocks data theft attempts
Operates your computer into stealth mode, making it invisible to intruders
Analyzes your inbox and Quarantines Internet worms and viruses
Monitors network activity of your PC
Protects your children from illegal, inappropriate web sites
Provides full access to a thorough history of your connections
Prevents data leak from your PC
Averts invasions of your privacy through the Internet
Conceals your surfing habits when browsing the Web
