tailieunhanh - CompTIA Network+ Certification Study Guide part 21

CompTIA’s Network+ certification Study Guide part 21 is a globally-recognized, vendor neutral exam that has helped over 235,000 IT professionals reach further and higher in their careers. The 2009 Network+ exam (N10-004) is a major update with more focus on security and wireless aspects of networking. Our new study guide has been updated accordingly with focus on network, systems, and WAN security and complete coverage of today’s wireless networking standards. | 186 CHAPTER 5 Wireless Networking zone to another. Many wireless-enabled devices such as laptops and hand-held computers use battery power and should be able to conserve power when not actively communicating with the network. Wireless communication over the air has to be secure to mitigate both passive and active attacks. WAP The WAP is an open specification designed to enable mobile wireless users to easily access and interact with information and services. WAP is designed for hand-held digital wireless devices such as mobile phones pagers twoway radios smartphones and other communicators. It works over most wireless networks and can be built on many operating systems OSs including PalmOS Windows CE JavaOS and others. The WAP operational model is built on the World Wide Web WWW programming model with a few enhancements and is shown in Figure . WAP browsers in a wireless client are analogous to the standard WWW browsers on computers. WAP URLs uniform resource locators are the same as those defined for traditional networks and are also used to identify local resources in the WAP-enabled client. The WAP specification added two significant enhancements to the abovementioned programming model push and telephony support wireless telephony application WTA . WAP also provides for the use of proxy servers as well as supporting servers that provide functions such as PKI support user profile support and provisioning support. Wireless Transport Layer Security FIGURE WAP Architecture Programming Model. Wireless Transport Layer Security WTLS is an attempt by the WAP Forum to introduce a measure of security into WAP. The WTLS Protocol is based on the Transport Layer Security TLS Protocol that is itself a derivative of the Secure Sockets Layer SSL Protocol. However several changes were made to these protocols to adapt them to work within WAP. These changes include Support for both datagram- and connection-oriented protocols Support for long round-trip times .