[GTALUG] Lightdm "Secure Remote connection"

[Giles Orr]

Lightdm offers as one of the options at the login screen, a "Secure
Remote connection" (this is on Debian jessie).  If this is selected,
you enter a username and password as usual, and when you click "Log
in" it asks for a "host:port" combination.  I haven't used this
before, so I guessed that 192.168.0.105:22 (a valid machine on my
network) would be appropriate.  After some cogitation and a bit of
screen flashing, this returns to the login prompt.

What settings do I need locally and remotely for this to work?  Where
should I look for errors?  Any thoughts?

A bunch of points that may help:
- ssh is installed on both machines, sshd is running and remote logins
work both ways
- the lightdm and lightdm-gtk-greeter packages are installed on both machines
- the remote machine is running Ubuntu trusty
- the remote user I'm trying to connect as is already running a local
X session on the remote machine: I'm assuming that doesn't matter?
- wireshark and the hard-to-read logs in /var/log/lightdm/ (on both
ends of the connection) suggest that ssh connects properly and X
starts ... and then fails, but I'm not clear on why.  Nor am I totally
sure I'm reading this right

- this feature appears to be totally undocumented: the interface
explains nothing, there's nothing in the man page, and even Google
knows nothing ... I even resorted to code diving, but "Secure Remote
connection" isn't in there.  It's also not anywhere in /etc/ where I
would have expected to find it if it was an option configured by
Debian (although it could be under /usr/ ... I haven't done a grep of
that entire tree ...)

Thanks for any assistance.

-- 
Giles
http://www.gilesorr.com/
gilesorr at gmail.com