Which of the following programs can be used to detect stealth port scans performed by a malicious hacker? Each correct answer represents a complete solution. Choose all that apply.

Nmap is a port scanning and host discovery tool used to conduct scans against target systems; it has no built-in capability to detect or alert on inbound scan attempts against the local host.

Scanlogd is a Unix daemon that passively monitors network traffic and logs suspected port scan attempts, directly fulfilling the role of a stealth scan detector.

Libnids is a network intrusion detection library that handles TCP/IP stream reassembly and includes logic for identifying port scanning patterns in captured traffic.

Portsentry actively monitors unused ports for scanning activity and can automatically block responding to or alerting on hosts detected performing port scans.