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XML in 60 Minutes a Day phần 2

ngăn chặn tin tặc, những người sẽ cố gắng để truy cập vào mạng thông qua máy chủ Web, được truy cập vào các máy chủ ứng dụng bảo mật cao hơn, đặc biệt là phân khúc riêng của một mạng lưới của tổ chức. DMZs đôi khi hy sinh để tin tặc, nhưng ít nhất các mạng tư nhân vẫn an toàn. | 42 Chapter 2 prevent hackers who would try to access the network through the Web server from gaining access to the higher-security application servers or especially to the private segment of an organization s network. DMZs are occasionally sacrificed to hackers but at least the private networks remain safe. Demilitarized Zone 2 DMZ2 . A group of servers on an intermediate security network segment that provide applications and services intended for Space Gems employees and their most trusted clients suppliers and so on. In this case all of Space Gems DMZ1 and DMZ2 systems likely have Web server software installed on them. There may also be Web server software installed on some private network systems. Now if an end user somewhere on the Internet enters the www.spacegems .com URL in his or her browser s location bar a request will be sent to the server that has been configured with the domain name spacegems that server is probably in DMZ1 here . After the server receives the request it responds by transmitting a page document designated by Space Gems to the requester s browser. Several domain names may be mapped to the same physical computer. This concept is called virtual hosting and the computer is called a virtual server. Virtual hosting allows you to provide several different Web sites each with its own domain name and even IP address using the same Web server system. Requests sent to these different sites will be routed by IP address hostname or browser language setting to the correct virtual host that is to its own respective Web site . Virtual hosting is a technique that will be illustrated in the lab exercises later in this chapter. Individual virtual hosts have unique Web root directories or folders directory or folder hierarchies default filenames and error files and restricted access files. On the other hand the different virtual host Web sites will likely share system caching plug-ins security realms and other features. Many Web server software .