312-50V13 Question #140: Real Exam Question with Answer & Explanation

Question

What does the following command in netcat do? nc ­l ­u ­p55555 < /etc/passwd

Options

• Alogs the incoming connections to /etc/passwd file
• Bloads the /etc/passwd file to the UDP port 55555
• Cgrabs the /etc/passwd file when connected to UDP port 55555
• Ddeletes the /etc/passwd file when connected to the UDP port 55555

Explanation

This netcat command sets up a UDP listener on port 55555 and redirects the contents of /etc/passwd as input, which will be sent to the first client that connects.

Common mistakes.

• A. The command redirects the content of /etc/passwd out over the network to a client, not incoming connections to the file.
• B. While it involves UDP port 55555, it doesn't 'load' the file to the port as if storing it; it streams its content through the port to a connecting client.
• D. The command uses input redirection (<), which reads from the file, it does not modify or delete it.

Concept tested. Netcat input redirection and listener mode for file transfer

Reference. https://linux.die.net/man/1/nc

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