Value of /proc/sys/kernel/hostname changes to hostname of neighbour computer

cafe_carl

I've set computer hostname in /etc/hostname a while ago (also there are record in /etc/hosts ). Everything worked fine, but recently I've noticed that value of hostname (and /proc/sys/kernel/hostname ) changed (to hostname of neighbour computer), although I haven't touched anything related. Value of /etc/hostname remains correct. Which mechanism may cause such change? There are similar problem description , but it doesn't contains any solution.

Originally asked by valodzka on Stack Exchange (unix) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

It's possible your kernel has autoconfiguration enabled and the DHCP server on your network is supplying this hostname. Usually the DHCP hostname is ignored if /etc/hostname is present (systemd-networkd does this, for example) but given the age of your question I would guess that whatever was handling network configuration at the time was taking the hostname from the DHCP response in preference to the one configured manually. If you want to check this, run a program such as Wireshark and have it listen to your network traffic. Type in a filter of dhcp and then unplug and replug your network cable. You should see the DHCP responses appear and you can examine them in the Wireshark window to...

Full answer by Malvineous: https://unix.stackexchange.com/a/663808 (CC BY-SA 4.0).

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