With significant firstboot output, there was a tendency
for tail to be killed before it relayed all the content.
Change to run the firstboot in a subshell in the background,
and have tail explicitly run until that subshell naturally
exits and then tail will cleanly exit
It is likely that a client connects from fe80::, which
is explicitly omitted from ssh principals.
This time, have the client provide all currently set IP addresses
and the server will make a determination.
There remains the possibility it misconfigures a nic and tries to use that,
inducing failure. One strategy would be to filter the addresses and
only provide from the 'current' interface. Another is to just take
the hit as the node is likely going to suffer a lot from such a
misconfiguration anyway.
