Firewalking is a technique that can be used to gather information about a remote network protected by a firewall. This technique can be used effectively to perform information gathering attacks. In this technique, an attacker sends a crafted packet with a TTL value that is set to expire one hop past the firewall. Which of the following are pre-requisites for an attacker to conduct firewalking?
Each correct answer represents a complete solution. Choose all that apply.
- ICMP packets leaving the network should be allowed.
- An attacker should know the IP address of the last known gateway before the firewall.
- There should be a backdoor installed on the network.
- An attacker should know the IP address of a host located behind the firewall.