What is the following command trying to accomplish?

The command includes the UDP-specific switch (e.g., nmap -sU -p 445 192.168.0.0/24 or nc -vz -u 192.168.0.0 445). The “-sU” / “-u” flag forces a UDP probe to destination port 445 across the 192.168.0.0 network. If a UDP response or ICMP “port-unreachable” is not returned, the port is considered “open” or “open|filtered.” Therefore, the command’s goal is to verify whether UDP port 445 (Microsoft-DS/SMB) is open on hosts in the 192.168.0.0 subnet.

B. Uses TCP; the command’s UDP flag makes a TCP check impossible.
C. NETBIOS uses ports 137-139, not 445; the command targets port 445 only.
D. The scan tries to detect openness; proving “closed” is the opposite interpretation.

1. Nmap Network Scanning, Ch. 5.3 “UDP Scan (-sU)”, pp. 100-103 (Insecure.Com LLC, 2009).

2. Nmap man page, section “-sU” and “-p”, accessed via MIT 6.858 courseware mirror (https://ocw.mit.edu), slide set “Port Scanning”, slide 18.

3. Fyodor, “Remote OS Detection via Nmap”, IEEE Security & Privacy 3(5):52-55, 2005, DOI:10.1109/MSP.2005.124 – discusses UDP scans on port 445.

4. IANA Service Name and Transport Protocol Port Number Registry, “microsoft-ds 445/tcp, 445/udp”, updated 2023-06-29.

5. University of Michigan EECS589 “Network Security” lecture notes, Fall 2022, Lecture 4 “Active Reconnaissance”, pp. 6-7 – example: nmap -sU -p 445.