What does the ACK evasion scan help determine?

What does the ACK evasion scan help determine?

• A. Whether the firewall is stateful or stateless and whether ports are open.
• B. The OS version.
• C. The VPN status.
• D. The NAT type.

Answer: (A)

Attackers use ACK evasion (ACK scan) to probe how a firewall handles unsolicited TCP ACKs. By sending ACK packets to various ports without completing a TCP connection, you observe how the target responds (or doesn’t). If the firewall is stateful, it tends to treat unsolicited ACKs carefully—often dropping them or producing specific responses—so the port appears filtered or unfiltered depending on the firewall rules. If the firewall is stateless, the behavior differs, and the host’s replies can reveal whether a port is effectively open or closed from the firewall’s perspective. In short, this scan helps determine whether a firewall is stateful or stateless and whether ports are effectively open (unfiltered) or blocked (filtered) by the firewall. OS version, VPN status, and NAT type are determined with other techniques, not via this scan.

Attackers use ACK evasion (ACK scan) to probe how a firewall handles unsolicited TCP ACKs. By sending ACK packets to various ports without completing a TCP connection, you observe how the target responds (or doesn’t). If the firewall is stateful, it tends to treat unsolicited ACKs carefully—often dropping them or producing specific responses—so the port appears filtered or unfiltered depending on the firewall rules. If the firewall is stateless, the behavior differs, and the host’s replies can reveal whether a port is effectively open or closed from the firewall’s perspective. In short, this scan helps determine whether a firewall is stateful or stateless and whether ports are effectively open (unfiltered) or blocked (filtered) by the firewall. OS version, VPN status, and NAT type are determined with other techniques, not via this scan.