What operating system would respond to the following command? C:\> nmap -sW 10.10.145.65

The correct answer is C. FreeBSD. The nmap -sW flag performs a TCP Window scan, which exploits an implementation quirk in how certain operating systems handle TCP RST packets. On most systems (Windows, Linux), the TCP window size in RST responses is always zero, making open and closed ports indistinguishable…

Submitted by daniela_cl· Apr 18, 2026Network Forensics

Question

What operating system would respond to the following command? C:> nmap -sW 10.10.145.65

Options

AWindows XP
BMac OS X
CFreeBSD
DWindows 95

How the community answered

(67 responses)

A
15% (10)
B
9% (6)
C
72% (48)
D
4% (3)

Explanation

The nmap -sW flag performs a TCP Window scan, which exploits an implementation quirk in how certain operating systems handle TCP RST packets. On most systems (Windows, Linux), the TCP window size in RST responses is always zero, making open and closed ports indistinguishable. However, FreeBSD (and some other BSD variants) set a non-zero TCP window value in RST responses for open ports, making the scan effective. The Window scan is most reliable against FreeBSD targets, which is why C is correct.

Topics

#Nmap#Window Scan#OS Fingerprinting#Network Scanning

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