Today I booted up and found my PTTYs missing. Not a good thing.
A quick look in ps-aux showed that ssh-agent was messing with them.
'rkill ssh' (R(egex)KILL is my own script) - killed it, and the PTTYs returned at once.
Now, on this system I have sshd disabled, and there should be no running ssh processes. Under no conditions should there be anything from the WAN able to see a login screen. I would as soon kill off ssh-agent, but am not sure if it is needed for normal communications, especially dealing with git, and Debian archives with all their crypto-verification stuff.
I dont know where the command is coming from. Not in /etc/init.d from what i can see and not in the /etc/xdg or ~/.config autostart files (here the latter are all blank). This is Devuan, but sysctl runs on this system. So the beast is here, just dunno where to look in /etc/systemd. Or elsehwere.
For now i can kill it in my .profile (rkill ssh) but eventually I would like to disable the entire command affecting PTTYs.