Which of the following statements are true about firewalking? Each correct answer represents a complete solution. Choose

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Which of the following statements are true about firewalking?
Each correct answer represents a complete solution. Choose all that apply.

A. To use firewalking, the attacker needs the IP address of the last known gateway before the firewall and the IP address of a host located behind the firewall.
B. Firewalking works on the UDP packets.
C. In this technique, an attacker sends a crafted packet with a TTL value that is set to expire one hop past the firewall.
D. A malicious attacker can use firewalking to determine the types of ports/protocols that can bypass the firewall.