اصول پيش زمينه و firewall 10 ص

تعداد صفحه : 24
- Background and Firewall Basics Before being able to understand a complete discussion of firewalls, its important to understand the basic principles that make firewalls work. What is a network firewall? A firewall is a system or group of systems that enforces an access control policy between two or more networks. The actual means by which this is accomplished varies widely, but in principle, the firewall can be thought of as a pair of mechanisms: one which exists to block traffic, and the other which exists to permit traffic. Some firewalls place a greater emphasis on blocking traffic, while others emphasize permitting traffic. Probably the most important thing to recognize about a firewall is that it implements an access control policy. If you dont have a good idea of what kind of access you want to allow or to deny, a firewall really wont help you. Its also important to recognize that the firewalls configuration, because it is a mechanism for enforcing policy, imposes its policy on everything behind it. Administrators for firewalls managing the connectivity for a large number of hosts therefore have a heavy responsibility. Why would I want a firewall? The Internet, like any other society, is plagued with the kind of jerks who enjoy the electronic equivalent of writing on other peoples walls with spraypaint, tearing their mailboxes off, or just sitting in the street blowing their car horns. Some people try to get real work done over the Internet, and others have sensitive or proprietary data they must protect. Usually, a firewalls purpose is to keep the jerks out of your network while still letting you get your job done. Many traditional-style corporations and data centers have computing security policies and practices that must be followed. In a case where a companys policies dictate how data must be protected, a firewall is very important