Có hai loại chính của tường lửa: phần cứng và phần mềm. Một bức tường lửa phần cứng là một thiết bị kết nối vào mạng trong một cách mà tất cả các thông tin liên lạc giữa các máy tính và Internet phải đi qua tường lửa và được kiểm tra để xem liệu họ nên được loại bỏ hoặc cho phép đi qua. | Chapter 10 Using Firewalls and Spyware Blockers 155 Figure 10-1 A firewall blocks unwanted communication from the Internet. There are two principal types of firewalls hardware and software. A hardware firewall is a device connected to the network in such a way that all communications between any computer and the Internet must pass through the firewall and be examined to see whether they should be discarded or allowed to pass through. A software firewall is a program that runs on a computer and performs the same type of examination of network communications that a hardware firewall does. But where a hardware firewall can protect all of the computers on a network a software firewall only protects the computer it is running on. Table 10-1 lists some of the pros and cons of hardware and software firewalls. Table 10-1 Comparison of Hardware and Software Firewalls Issue Hardware Firewall Software Firewall Protection All computers on One computer only the network Portability Forget it Goes everywhere your computer goes continued 156 Part III Maintaining Your Vigilance Table 10-1 continued Issue Hardware Firewall Software Firewall Cost 40- 200 No freebies 30- 60 Some are free Ease of initial setup Easy to moderate Easy to moderate Ease of configuration Easy to moderate Easy to moderate Impact on PC performance Zero Negligible Blinking Lights Some None Available via download Rarely Often Software firewalls A software firewall is a program that runs inside your computer and blocks unwanted network traffic as shown in Figure 10-2. Software firewalls are a necessity for any laptop computer especially one that connects to the Internet from a variety of locations. Wherever your laptop goes so too goes your firewall because it s right there inside. But if you have a desktop computer and you connect to the Internet using a dial-up modem you ve got to get a software firewall to protect it. Sometimes software firewalls are known as personal firewalls so named because they are your .
