nerdexam
EC-Council

312-50V13 · Question #357

You have compromised a server on a network and successfully opened a shell. You aimed to identify all operating systems running on the network. However, as you attempt to fingerprint all machines in…

The correct answer is D. OS Scan requires root privileges. The Nmap error message and the requirement for TCP/IP fingerprinting indicate that the OS scan (-O) failed because Nmap requires root privileges to craft and send raw packets for accurate operating system detection.

Submitted by helene.fr· Mar 6, 2026Scanning Networks

Question

You have compromised a server on a network and successfully opened a shell. You aimed to identify all operating systems running on the network. However, as you attempt to fingerprint all machines in the network using the nmap syntax below, it is not going through. invictus@victim_server.~$ nmap ­T4 ­O 10.10.0.0/24 TCP/IP fingerprinting (for OS scan) xxxxxxx xxxxxx xxxxxxxxx. QUITTING! What seems to be wrong?

Options

  • AThe nmap syntax is wrong.
  • BThis is a common behavior for a corrupted nmap application.
  • CThe outgoing TCP/IP fingerprinting is blocked by the host firewall.
  • DOS Scan requires root privileges.

How the community answered

(47 responses)
  • A
    15% (7)
  • B
    4% (2)
  • C
    2% (1)
  • D
    79% (37)

Why each option

The Nmap error message and the requirement for TCP/IP fingerprinting indicate that the OS scan (`-O`) failed because Nmap requires root privileges to craft and send raw packets for accurate operating system detection.

AThe nmap syntax is wrong.

The Nmap syntax `nmap -T4 -O 10.10.0.0/24` is syntactically correct for an OS scan on the specified subnet with a timing template.

BThis is a common behavior for a corrupted nmap application.

While a corrupted application can cause issues, the specific error message concerning 'TCP/IP fingerprinting' directly points to a functional limitation (lack of privileges) rather than a general application corruption.

CThe outgoing TCP/IP fingerprinting is blocked by the host firewall.

If a host firewall were blocking the outgoing TCP/IP fingerprinting, Nmap would likely report timeouts or filtered ports, not a 'QUITTING!' message that suggests a local operational failure due to insufficient permissions.

DOS Scan requires root privileges.Correct

Nmap's OS detection feature, activated by the `-O` flag, requires root (or administrator on Windows) privileges to craft and send raw IP packets necessary for TCP/IP fingerprinting. Without these elevated permissions, the operating system prevents Nmap from performing the low-level network operations needed for OS detection, leading to the 'QUITTING!' error.

Concept tested: Nmap OS detection and root privileges

Source: https://nmap.org/book/man-root-privileges.html

Topics

#Nmap#OS detection#privilege escalation#scanning issues

Community Discussion

No community discussion yet for this question.

Sign up to join the discussion
Full 312-50V13 Practice