The man page for rngd says there is an option -S to control the interval at which stats are written to sylog. I would like to change that interval but I can't find where rngd is started at boot (which, I presume, is where I would add the -S option). This is on "bullseye". Can anyone help? My google-fu has failed me on this.



  • What's in /etc/defaults for rngd? That's where you usually put startup parm overrides. Else edit the systemd rngd.service file and add the option in there.
    – Dougie
    Feb 16 at 16:57

2 Answers 2


Thanks to Dougie, I edited the file /etc/default/rng-tools-debian and added a line RNGDOPTIONS="-S 86400" (to give me a 1 day interval) followed by a sudo systemctl restart rng-tools.service and that looks like it will do the trick.


In general listing files which belong to a package usually helps finding its configs. If you have rngd installed, you can run dpkg -L rng-tools-debian, otherwise you can look at the package contents in the Debian catalog.

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