Chúng tôi mạnh mẽ khuyên bạn nên xem xét sử dụng một bên thứ ba sản phẩm xác thực hai-yếu tố chẳng hạn như bị mạng thay vì bởi vì điều này cung cấp xác thực đến nay mạnh mẽ hơn và giúp loại bỏ một số vấn đề tiềm năng với các cuộc tấn công từ chối dịch vụ. | 184 Part III Using Your Network Securely Minimize eliminate operational losses Minimize investment Maximize positive returns where ROI applies Accelerate the timing of returns Your goal is to implement cost-effective security in which the expected cost of a control is less than the expected loss. Such controls generate a positive ROSI that is you can expect to save money over time. Ideally you want to deploy the most cost-effective controls those that maximize ROSI. Your challenge is to measure ROSI for given security controls. You should try to base measurements on empirical data and mathematical analysis rather than opinions. You should evaluate all proposals techniques products and services in terms of ROSI. You should establish best practices based on ROSI. Unfortunately most companies currently base security decisions on expert opinion and conventional wisdom not on empirical data and mathematical analysis. Perform a risk assessment to understand the value of the assets in your organization that need protection. Understanding the value of organizational assets and the level of protection required is likely to enable more costeffective wireless solutions that provide an appropriate level of security. You don t want to spend money to protect data that has no value. We doubt that you will find any case in which the data has no value but you don t want to spend more on security measures than the value of the data. Several companies sell risk management software including Methodware Enterprise Risk Assessor and Risk Services Technology RiskTrak . Chapter 11 Maintaining Network Security Jn This Chapter Reviewing security mechanisms Understanding authentication Filtering SSIDs MAC addresses and protocols Encrypting frames Looking at WEP problems Upgrading to WPA Using AES Using EAP 1. n this chapter we look at several built-in security features of for network security. Risks in wireless networks are equal to the sum of the .