计算机专业英语 郭敏 计算机专业英语Unit4.pptVIP

Unit 4 Section 2 Passage A record physical device Compiler Loader Linker Interpreter Java architecture Intel Pentium Execution boot shut down power off Editor Library machine code address space Instruction database Unit 4 Section 2 Passage B safeguard thread misuse bug privacy password Anti-virus firewall unauthorized intranet security criteria packet filter IP gateway FTP Telnet TCP Unit 4 Section 2 Passage B There are several types of firewall techniques： Packet filter Application gateway Circuit-level gateway Proxy server Unit 4 Section 2 Passage B 1. Packet filter Packet filtering inspects each packet passing through the network and accepts or rejects it based on user-defined rules. Although difficult to configure, it is fairly effective and mostly transparent to its users. It is susceptible to IP spoofing. 2. Application gateway The application gateway applies security mechanisms to specific applications, such as FTP and Telnet servers. This is very effective, but can impose a performance degradation. 3. Circuit-level gateway The circuit-level gateway applies security mechanisms when a TCP or UDP connection is established. Once the connection has been made, packets can flow between the hosts without further checking. 4. Proxy server The proxy server intercepts all messages entering and leaving the network. It effectively hides the true network. Unit 4 Section 2 Passage B Antivirus (or anti-virus) software is used to prevent, detect, and remove malware, including computer viruses, worms, and Trojan horses. Such programs may also prevent and remove spyware, adware, and other forms of malware. Here are the major types of anti-virus software: Traditional antivirus programs Anti-adware programs Anti-spyware programs Trojan horse removal programs Unit 4 Section 2 Passage B 1. Traditional antivirus programs Generically labeled “Antivirus Software” is the main type of antivirus software used by consumers. It eliminates most viral infections, but does not alw