So I upgraded some 5xxx appliances from R77.30 to R80.10 using CPUSE. I didn't read the upgrade instructions, like I did in the old days with IPSO. Partially because Check Point makes it very easy to upgrade with CPUSE, partially because I did not expect the thing to happen, that happened to my DHCP configuration.
You see - as soon as you need any DHCP Option other than DNS, Router or Domain, you're forced to manually craft your own little dhcpd.conf.
During the automated upgrade, this dhcpd.conf is overwritten and the original state is lost, ignoring the fact, that you have set this file to immutable (chattr +i) before.
We're in 2018. Free and open source firewalls such as pfSense have a GUI which allows the creation of custom DHCP options for more than 10 years now. But Check Point? Buy some crazy snake oil threat prevention thingy! New and shiny! Software Blades! Woooop! But a simple thing, such as custom DHCP options? Rocket science.
Sorry for the rant. I had to.
And no worries: I had a backup of the dhcpd.conf.