A legacy host runs its telnet service under xinetd, configured in /etc/xinetd.d/telnet. Which change turns the service off while keeping the configuration file in place?
LPIC-1 Exam 102-500, objective 110. Security medium
Draft — not checked yet. This question was written from the published exam objectives and cites the clause it comes from, but nobody has yet read it against that clause and signed for it.
It is kept out of search results and out of mock exams until they have. Read the source below before you take the answer as settled.
The options
Correct Add or set `disable = yes` inside the service block, then reload xinetd.
Correct. disable = yes is the per-service switch xinetd reads. Reloading xinetd (or sending it SIGHUP) makes it stop listening on that port.
Not correct Set `wait = yes` inside the service block.
Wrong. wait selects the threading model: yes means xinetd hands the socket to a single-threaded server and waits for it to exit (typical for UDP), no means it forks a new server per connection (typical for TCP). It does not disable anything.
Not correct Comment the telnet line out of /etc/inetd.conf.
Wrong on this host. /etc/inetd.conf is the configuration of the older inetd superserver, which xinetd replaces. xinetd never reads it, so the service keeps running.
Not correct Set `server = /bin/false` inside the service block.
Wrong. server names the program xinetd executes for each connection. xinetd would still accept connections on the telnet port and simply run /bin/false, so the port stays open.
Why
xinetd keeps one file per service under /etc/xinetd.d, included by /etc/xinetd.conf, and each block carries attributes such as socket_type, protocol, user, server, server_args, wait and disable. The classic inetd instead uses single lines in /etc/inetd.conf, which you disable by commenting out and then signalling inetd to re-read its configuration. On current systemd distributions both superservers are largely gone: services are units, and you disable one permanently with `systemctl disable --now telnet.socket`.
Where this comes from
- Cited
- LPI exam objective 110.2
- What it says
- Turn off unused network services offered by inetd or xinetd.
Practise this
Reading one question is not practice. The trainer will draw a set from objective 110 and space the ones you get wrong.