An administrator runs `ss -tulpn`. What does the `p` in that flag cluster add to the output?
LPIC-1 Exam 102-500, objective 109. Networking fundamentals medium
Machine-checked — no person has signed for it. This question was read against the source cited below by an automated pass, which found no contradiction. That is a weaker claim than it sounds: the same kind of process wrote the question, so it can confirm its own mistake.
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How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Not correct It prints the protocol name of each socket
Wrong. The protocol is already implied by -t (TCP) and -u (UDP) and shown in the first column. No ss flag is needed for it.
Correct It shows the process name and PID that owns each socket
Correct. -p (--processes) attaches the owning process to each socket line. You need root to see processes belonging to other users; without privileges the column is mostly blank.
Not correct It restricts the listing to sockets in the LISTEN state
Wrong. That is -l (--listening). -l is the flag that turns this command into a listening-ports report.
Not correct It resolves numeric ports to service names from /etc/services
Wrong, and backwards. ss resolves names by default; -n (--numeric) is the flag that suppresses resolution and shows raw numbers.
Why
In `ss -tulpn`: -t TCP, -u UDP, -l listening sockets only, -p owning process, -n numeric (no port or host name resolution). ss ships with iproute2 and is the modern replacement for netstat, whose closest equivalent is `netstat -tulpn`.
Where this comes from
- Cited
- manual page ss(8)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 109 and space the ones you get wrong.
More questions on this objective
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