tailieunhanh - Suse Linux 9.3 For Dummies- P11

Suse Linux For Dummies- P11:This part is all about getting you started on your way to a lasting relationship with SUSE Linux. Before you can begin your SUSE Linux experience, I spend a chapter explaining what SUSE Linux is and what you can do with SUSE Linux (pretty much anything you can do with a PC that runs Windows). | 130 Part II Test Driving SUSE__ Understanding Wired Equivalent Privacy WEP The standard includes Wired Equivalent Privacy WEP for protecting wireless communications from eavesdropping. WEP relies on a 40-bit or 104-bit secret key that is shared between a mobile station such as a laptop with a wireless Ethernet card and an access point also called a base station . The secret key is used to encrypt data packets before they transmit and an integrity check is performed to ensure that packets are not modified in transit. The standard does not explain how the shared key is established. In practice most wireless LANs use a single key that is shared between all mobile stations and access points. Such an approach however does not scale up very well to an environment such as a college campus because the keys are shared with all users and you know how it is if you share a secret with hundreds of people. That s why WEP is typically not used on large wireless networks such as the ones at universities. In such wireless networks you have to use other security approaches such as SSH Secure Shell to log in to remote systems. WEP however is good to use on your home wireless network. WEP has its weaknesses but it s better than nothing. You can use it in smaller wireless LANs where sharing the same key among all wireless stations is not an onerous task. w Work is underway to provide better security than WEP for wireless networks. A standard called is in the works that provides better security through public-key encryption. While the standard is in progress the Wi-Fi Alliance a multivendor consortium that supports Wi-Fi has developed an interim specification called Wi-Fi Protected Access WPA that s a precursor to . WPA replaces the existing WEP standard and improves security by making some changes. For example unlike WEP which uses fixed keys the WPA standard uses something called the .