ACK Flag Probe Scan
Introduced as a network scanning technique, the ACK Flag Probe Scan surfaced in cybersecurity discourse to assess the status of a target system's firewall. Originating prior to its documentation, this method leverages the Transmission Control Protocol (TCP) ACK (acknowledgment) flag to send packets to the target system. Upon analyzing the responses, typically through tools like Nmap or hping, cybersecurity professionals can discern whether a port is open, closed, or filtered by a firewall. A response of an RST (reset) packet usually indicates an open port, while an ICMP (Internet Control Message Protocol) unreachable message signifies a closed port. A lack of response or an ICMP error message suggests a filtered port, possibly due to firewall configuration. ACK Flag Probe Scans are often employed alongside other scanning techniques to gather comprehensive information about a system's network configuration and security posture. Nmap and hping are popular tools used for conducting ACK Flag Probe Scans.