ISC2 Exam ISSEP Topic 2 Question 15 Discussion

Packet filtering is a method that allows or restricts the flow of specific types of packets to provide

security. It analyzes the incoming and

outgoing packets and lets them pass or stops them at a network interface based on the source and

destination addresses, ports, or

protocols. Packet filtering provides a way to define precisely which type of IP traffic is allowed to

cross the firewall of an intranet. IP packet

filtering is important when users from private intranets connect to public networks, such as the

Internet.

Answer option B is incorrect. An application gateway firewall applies security mechanisms to specific

applications, such as FTP and Telnet

servers. This is very effective, but can impose a performance degradation.

Answer option A is incorrect. A circuit-level gateway firewall 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.

Answer option C is incorrect. A proxy server firewall intercepts all messages entering and leaving the

network. The proxy server effectively

hides the true network addresses.