Idea for dynamic DNS (e.g. you have DHCP on your WAN at home): instead of polling every 5 minutes: what's my IP? has it changed?
What about scripting something with devd.conf(5) for ADDR_ADD / ADDR_DEL? i.e. catchthe event and launch a script to set DNS.
https://man.freebsd.org/cgi/man.cgi?query=devd.conf&sektion=5
@dvl I've been using /etc/dhclient-exit-hooks for that at home.
[ ."$reason" = .BOUND ] and [ ."$reason" = .RENEW ] will pass the new IP to a shellscript that updates my records at bunny.net DNS via their REST API.
@dvl usually you don't (and shouldn't) touch /sbin/dhclient-script. That script is invoked by dhclient and it sources /etc/dhclient-enter-hooks and /etc/dhclient-exit-hooks - those are the files you want to use to add custom behavior and e.g. run your own scripts to which you can pass the variables set by dhclient (e.g. $new_ip_address).
e.g. I'm calling my ddns script from /etc/dhclient-exit-hooks as follows:
[ ."$reason" = .BOUND ] && /usr/home/sko/bunny_ddns.sh -n <recordID> -i $new_ip_address -k <APIkey> -z <zoneID>
that script then basically just mangles the input data into a curl POST request for the API.
I always wanted to look into using the "EXPIRE", "FAIL" and "TIMEOUT" reasons to switch over to a fallback uplink...
@sko The first of two posts:
https://dan.langille.org/2025/03/02/when-my-home-dhcp-address-changes-i-want-stuff-done/
Dan Langille
sko