Allow to run SSHd in Installer (12.2 patch)

[Ben RUBSON]

Hi,

I've done some work to allow to connect to FreeBSD installer through SSH.
It can be useful for example if we have specific tasks to perform before installation, such as disks configuration etc...
Working through a SSH connection is much more convenient than in front of a console.
FreeBSD installer can then also be used as a rescue disk.

To achieve this, I've modified FreeBSD installer, so that after having installed SSHd, if performs following configuration modifications :
- generate host keys into /var/ssh (as default /etc/ssh is not writable) ;
- only allow keys authentication ;
- allow root authentication ;
- read authorized_keys file from /var/ssh (as default homedirs are not writable).

SSHd can then be started thanks to the installer shell : service sshd start
And a public key put into for example /var/ssh-keys/root/authorized_keys, thanks to fetch or whatever.

Work is here :
https://github.com/freebsd/freebsd/pull/156
Rather simple, and ready to be merged.

This job is more than 2 years old, I would then really be glad if we could see this in 12.2 installation ISOs.
It would prevent me from having to modify the new ISO files to implement this patch.

Many thanks !

Best regards,

Ben