firewall is a system or group of systems that enforces an access control policy between two networks clark.net
the main purpose of a firewall system is to control access to or from a protected network. It implements a network access policy by forcing connections to pass through the firewall, where they can be examined and evaluated csrc.ncsl.nist.gov
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Showing posts with label Internet Security. Show all posts
Showing posts with label Internet Security. Show all posts
Tuesday, September 9, 2008
Internet Security
The Internet is global in scope, but this global internetwork is an open insecure medium. The Internet has revolutionised the computing and communications world for the purpose of development and support of client and server services. The availability of the Internet, along with powerful affordable computing and communications, has made possible a new paradigm of commercial world. This has been tremendously accelerated by the adoption of browsers and World Wide Web technology, allowing users easy access to information linked throughout the globe. The Internet has truly proven to be an essential vehicle of information trade today.
The Internet is today a widespread information infrastructure, a mechanism for information dissemination, and a medium for collaboration and interaction between individuals, government agencies, financial institutions, academic circles and businesses of all sizes, without regard for geographic location. People have become increasingly dependent on the Internet for personal and professional use regardless of whether it is for e-mail, file transfer, remote login, Web page access or commercial transactions. With the increased awareness and popularity of the Internet, Internet security problems have been brought to the fore. Internet security is not only extremely important, but more technically complex than in the past. The mere fact that business is being performed online over an insecure medium is enough to entice criminal activity to the Internet.
The Internet access often creates a threat as a security flaw. To protect users from Internetbased attacks and to provide adequate solutions when security is imposed, cryptographic techniques must be employed to solve these problems. This book is designed to reflect the central role of cryptographic operations, principles, algorithms and protocols in Internet security. The remedy for all kinds of threats created by criminal activities should rely on cryptographic resolution. Authentication, message integrity and encryption are very important in cultivating, improving, and promoting Internet security.Without such authentication procedures, an attacker could impersonate anyone and then gain access to the network. Message integrity is required because data may be altered as it travels through the Internet. Without confidentiality by encryption, information may become truly public.
Firewall and Proxy Server
A firewall is a structure intended to keep a fire from spreading. Building have firewalls made of brick walls completely dividing sections of the building. In a car a firewall is the metal wall separating the engine and passenger compartments. Internet firewalls are intended to keep the flames of Internet hell out of your private LAN. Or, to keep the members of your LAN pure and chaste by denying them access the all the evil Internet temptations.;−) The first computer firewall was a non−routing Unix host with connections to two different networks. One network card connected to the Internet and the other to the private LAN. To reach the Internet from the private network, you had to logon to the firewall (Unix) server. You then used the resources of the system to access the Internet. For example, you could use X−windows to run Netscape's browser on the firewall system and have the display on your work station. With the browser running on the firewall it has access to both networks.
This sort of dual homed system (a system with two network connections) is great if you can TRUST ALL of your users. You can simple setup a Linux system and give an account accounts on it to everyone needing Internet access. With this setup, the only computer on your private network that knows anything about the outside world is the firewall. No one can download to their personal workstations. They must first download a file to the firewall and then download the file from the firewall to their workstation. BIG NOTE: 99% of all break−ins start with gaining account level access on the system being attacked. Because of this I don't recommend this type of firewall. It is also very limiting.
Firewall Protection
What is a Firewall?
A firewall is a tool that monitors communication to and from your computer. It sits between your computer and the rest of the network, and according to some criteria, it decides which communication to allow, and which communication to block. It may also use some other criteria to decide about which communication or communication request to report to you (either by adding the information to a log file that you may browse whenever you wish, or in an alert message on the screen), and what not to report.
What Is It Good For?
Identifying and blocking remote access Trojans. Perhaps the most common way to break into a home computer and gain control, is by using a remote access Trojan (RAT). (sometimes it is called "backdoor Trojan" or "backdoor program". Many people simply call it a "Trojan horse" although the term "Trojan horse" is much more generic). A Trojan horse, is a program that claims to do something really innocent, but in fact does something much less innocent. This goes to the days where the Greek soldiers succeeded to enter through the gates of Troy by building a big wooden horse, and giving it as a present to the king of Troy. The soldiers allowed the sculpture to enter through their gates, and then at night, when the soldiers were busy guarding against an outside attack, many Greek soldiers who were hiding inside the horse went out and attacked Troy from the inside. This story, which may or may not be true, is an example of something which looks like something innocent and is used for some less innocent purpose. The same thing happens in computers.
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