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
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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 set from objective 109 and space the ones you get wrong.