Using the iproute2 socket utility, list only listening TCP sockets, with ports and addresses left as numbers rather than resolved to service and host names. Type the complete command, using short options only.
LPIC-1 Exam 102-500, objective 110. Security 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.
Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.
How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
Answer
Type the answer.
Accepted answers
ss -tlnss -tnlss -ltnss -lntss -ntlss -nltss -t -l -nss -t -n -lss -l -t -nss -l -n -tss -n -t -lss -n -l -t
Case sensitive — Linux is, and grading LS as ls would teach a falsehood.
Why
ss -tln is the modern replacement for netstat -tln. -t restricts output to TCP, -l shows only sockets in the listening state, and -n suppresses name resolution so you see 22 rather than ssh and 0.0.0.0 rather than a hostname. Add -u to include UDP and -p to show the owning process, which requires root to be useful. The equivalent netstat invocation is `netstat -tlnp`, but netstat comes from the deprecated net-tools package and is not installed by default on many current distributions.
Where this comes from
- Cited
- LPI exam objective 110.1
- What it says
- Discover open network ports and the services listening on them.
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 110 and space the ones you get wrong.
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