I remember some ops back in the day putting ads into /etc/motd (https://en.wikipedia.org/wiki/Message_of_the_day https://en.wikipedia.org/wiki/Message_of_the_da

I remember some ops back in the day putting ads into /etc/motd (https://en.wikipedia.org/wiki/Message_of_the_day https://en.wikipedia.org/wiki/Message_of_the_day) for free/cheap servers/services too, 2-3 decades ago.