Firewall

=Firewall= Author: Tommy Choi Firewall is software now widely used in many parts of world where ever computer is. This software is designed to block unauthorized access while permitting authorized access communication. It inspects network traffic passing through it. Compare to our school, fire wall is front door where security check every people passing. This kind of technology emerged in 1980s when internet started to use widely. There are three generations (and there are more and more types are coming out) that developed as internet become wider and way of hacking become smarter. Name

1st generation is packet filters -In 1998, engineers from Digital Equipment Corporation (DEC) developed filter systems. -This became highly evolved in internet security. -Packet filtering inspects each packets passing through the network and according to set of rules that user made it accepts or rejects packet. 2nd generation is application layer -"Understand" certain application & protocols, it can detect unwanted protocol sneaking in to computer from non-standard port or protocol is abused in any harmful way. -All seven layers of the OSI reference model worked on by this. -Can filter higher level protocol -"For example, if an organization wants to block all the information related to "foo" then content filtering can be enabled on the firewall to block that particular word. This is a software based firewall and thus it is much slowerthan a stateful firewall." 3rd generation is 'stateful' filters. -1989~1990 three colleagues from AT&T Bell Laboratories, Dave Presetto, Janardan Sharma, and Kshitij Nigam developed circuit level firewalls. Subsequent Developments. -1992 Bob Braden and Annette DeSchon were refining the concept of a fire wall. -1994 Israeli company called Check Point Software Technologies built this into readily available software known as FireWall-1 -"Currently, the Middlebox Communication Working Group of the Internet Engineering Task Force (IETF) is working on standardizing protocols for managing firewalls and other middleboxes."

4 types of fire wall techniques
 * 1) "[|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]. "
 * 2) "[|Application gateway]: Applies security mechanisms to specific applications, such as [|FTP] and [|Telnet] servers. This is very effective, but can impose a performance degradation. "
 * 3) "[|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. "
 * 4) "[|Proxy server]: Intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses." ([])

(Everything here reference to http://en.wikipedia.org/wiki/Firewall_(computing) (Mr. Aleman my house internet so slow that reference is not working so i'll write reference here)

[|Wikipedia]