Certified Ethical Hacker CEH · Free Practice Question Easy
Question 16
Danny, a black hat hacker, used Nmap to scan a network. Output confirmed presence of a firewall. Now he wants to determine whether it is a stateful or stateless firewall. Which of the following options will be useful for Danny?
- A A. "-sS"
- B B. ”-sT”
- C C. ”sU”
- D D. ”-sA”
Reveal correct answer
Correct answer: D
Explanation
Correct Answer: D. ”-sA” Explanation: A."-sS" (TCP SYN scan): This option sends a TCP SYN packet to the target host and listens for a response. This is the default scan type when no other is specified, as it is fast and stealthy. Stealth scanning is performed by sending an SYN packet and analyzing the response. If SYN/ACK is received, it means the port is open, and you can open a TCP connection. However, a stealth scan never completes the 3-way handshake, which makes it hard for the target to determine the scanning system. B."-sT" (TCP connect scan): This option creates a full TCP connection to the target port, which is more reliable but also more detectable than a SYN scan. C."-sU" (UDP scan): This option is used to scan for open UDP ports, which are commonly used for DNS, SNMP, and other network services. D. “-sA” (TCP ACK Scan): This scan is used to map out firewall rulesets, determining whether they are stateful or not and which ports are filtered.Discussion
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