tailieunhanh - cwna certified wireless network administrator official study guide phần 9

, bộ khuếch đại phải được cấu hình cho số tiền thích hợp khuếch đại cần thiết, theo tính toán toán học RF của bạn. Hướng dẫn sử dụng của nhà sản xuất sẽ giải thích làm thế nào để chương trình hoặc cấu hình bộ khuếch đại. | 277 Chapter 10 - Wireless LAN Security in such a manner as to avoid the weaknesses with WEP such as the initialization vector problem. Temporal Key Integrity Protocol TKIP TKIP is essentially an upgrade to WEP that fixes known security problems in WEP s implementation of the RC4 stream cipher. TKIP provides for initialization vector hashing to help defeat passive packet snooping. It also provides a Message Integrity Check to help determine whether an unauthorized user has modified packets by injecting traffic that enables key cracking. TKIP includes use of dynamic keys to defeat capture of passive keys a widely publicized hole in the existing Wired Equivalent Privacy WEP standard. TKIP can be implemented through firmware upgrades to access points and bridges as well as software and firmware upgrades to wireless client devices. TKIP specifies rules for the use of initialization vectors re-keying procedures based on per-packet key mixing and message integrity code MIC . There will be a performance loss when using TKIP but this performance decrease may be a valid trade-off considering the gain in network security. AES Based Solutions AES-based solutions may replace WEP using RC4 but in the interim solutions such as TKIP are being implemented. Although no products that use AES are currently on the market as of this writing several vendors have products pending release. AES has undergone extensive cryptographic review and is very efficient in hardware and software. The current draft specifies use of AES and considering most wireless LAN industry players are behind this effort AES is likely to remain as part of the finalized standard. Changing data encryption techniques to a solution that is as strong as AES will make a significant impact on wireless LAN security but there still must be scalable solutions implemented on enterprise networks such as centralized encryption key servers to automate the process of handing out keys. If a client radio card is .