Allow to run SSHd in Installer (12.2 patch)

[Rodney W. Grimes]

I have been starting sshd from install media since 5.4 or so,
here is my current method that should work on 11, 12 and 13:

# This version for FreeBSD 11.0R, works for 12.0 too

mkdir /tmp/ssh
cp -p /etc/ssh/sshd_config /tmp/ssh
echo 'PermitRootLogin yes' >> /tmp/ssh/sshd_config
echo 'AllowGroups wheel' >> /tmp/ssh/sshd_config
echo 'PermitEmptyPasswords yes' >> /tmp/ssh/sshd_config
echo 'HostKey /tmp/ssh/ssh_host_rsa_key' >> /tmp/ssh/sshd_config
echo 'HostKey /tmp/ssh/ssh_host_dsa_key' >> /tmp/ssh/sshd_config
echo 'UsePAM no' >> /tmp/ssh/sshd_config
echo 'PasswordAuthentication yes' >> /tmp/ssh/sshd_config

ssh-keygen -t rsa -f /tmp/ssh/ssh_host_rsa_key -N ''
ssh-keygen -t dsa -f /tmp/ssh/ssh_host_dsa_key -N ''

/usr/sbin/sshd -f /tmp/ssh/sshd_config

For those that "need" this feature today :-)  Just drop to
a shell after booting from install media, run the above
commands, and you can get in.  BEWARE, passwordless root login enabled!
 
> Hi Ben,
> 
> I'm not a FreeBSD developer (so not your targeted audience) but would 
> very much like to see this land in a release!
> 
> Kind regards,
> 
> Ruben
> 
> On 3/10/20 4:07 PM, Ben RUBSON wrote:
> >> On 2 Mar 2020, at 13:09, Ben RUBSON <ben.rubson at gmx.com> wrote:
> >>
> >> 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.
> > 
> > Any thoughts ? :)
> > 
> > Thank you very much !
> > 
> > Ben
> > 
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-- 
Rod Grimes                                                 rgrimes at freebsd.org