You can also use IPSec with manual keys which works out of the box tools and is standard, interops with other platforms as well, even with router OSes. On linux

You can also use IPSec with manual keys which works out of the box tools and is standard, interops with other platforms as well, even with router OSes. On linux side eg like this: https://unix.stackexchange.com/questions/638436/rekey-ipsec-using-ip-xfrm https://unix.stackexchange.com/questions/638436/rekey-ipsec-...