Return DNS port on ">dns-port" telnet command

[DL6ER]

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• I have read and understood the contributors guide.
• I have checked that another pull request for this purpose does not exist.
• I have considered, and confirmed that this submission will be valuable to others.
• I accept that this submission may not be used, and the pull request closed at the will of the maintainer.
• I give this submission freely, and claim no ownership to its content.

How familiar are you with the codebase?:

10

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See title.

Example:

$ echo ">dns-port >quit" | nc 127.0.0.1 4711
53

Meant to be useful for pi-hole/pi-hole#4485. Can be closed without merging when not used there. Note that the port can also be 0 is someone decides to disable the DNS server part of Pi-hole (possible even when not useful).

[yubiuser]

Documentation PR: pi-hole/docs#629

[yubiuser]

Thanks.

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pi-hole-ftl-v5-13-web-v5-10-and-core-v5-8-released/52254/1