Announcing printerd

Posted May 22, 2012 14:31 UTC (Tue) by nix (subscriber, #2304)
Parent article: Announcing printerd

I'd not mind this increasing emphasis on D-Bus if there was a sane way to allow D-Bus session bus connections to be tunnelled over the network. Unfortunately it seems we currently have two possibilities:

- local AF_UNIX sockets with randomly-assigned names in a fixed directory, with a name exported via an environment variable (the default). Local system only, you're on a remote system? Sucks to be you.

- remote IP connection, not really per-session as there is no automatic port assignment, SSH forwarding or anything else. i.e. you can say

<listen>tcp:host=localhost,bind=*,port=10315</listen>

in session.conf, but what you cannot say is 'assign a port automatically, and export it in an environment variable', let alone 'get SSH to forward-and-proxy a connection to the dbus session bus', which would allow a secure session bus across the network. This is not rocket science -- it's the preferred way of handling X connections -- but as far as I can see D-Bus is incapable of it. Am I wrong?

(Obviously doing this securely would involve -- fairly trivial -- changes to OpenSSH as well.)

Announcing printerd

Posted May 22, 2012 16:22 UTC (Tue) by randomguy3 (subscriber, #71063) [Link]

That would be nice, but for most of its uses, you don't want it running over the network. Consider upower or udisks, for example, which control inherently local operations. It's not as though they replace something network-transparent, either. If you want to operate on a machine, run the application on that machine (which you can do with ssh). X-over-ssh is really a different thing, as it's about allowing interaction with graphical applications on a remote machine, the same way normal SSH works for console programs.

In the case of printerd, I think it's meant to be a purely local printing framework. If you want a print server, run Cups. Or Samba. printerd can then make use of either of those servers, but applications only talk directly to the local printerd (in the same way they might talk directly to a local character device in /dev, say).

And the announcement does suggest that there will be an IPP interface along soon, which is the right way to do printing over the network, really.

Announcing printerd

Posted May 23, 2012 12:28 UTC (Wed) by krake (guest, #55996) [Link] (4 responses)

"This is not rocket science -- it's the preferred way of handling X connections -- but as far as I can see D-Bus is incapable of it. Am I wrong?"

Can you explain how SSH can be used to forward Unix sockets other than X11's?

I have been looking for that for years but never found any example on how to do that.
Since it works for X11 it can't be rocket science but so far all indicators I've seen say that SSH is incapable of it.

Announcing printerd

Posted May 24, 2012 0:28 UTC (Thu) by nix (subscriber, #2304) [Link] (3 responses)

You can't forward AF_UNIX sockets with OpenSSH generally :( like I said, doing this properly requires changes to OpenSSH too.

Announcing printerd

Posted May 24, 2012 9:31 UTC (Thu) by hppnq (guest, #14462) [Link] (2 responses)

Perhaps one could use socat.

Announcing printerd

Posted May 28, 2012 13:01 UTC (Mon) by nix (subscriber, #2304) [Link]

Probably. After all, socat can do anything. Downside: reading the manual requires dark rites first to prevent your brain dribbling out of your ears. It's the Emacs of netcats.

forwarding unix-domain sockets over ssh [was: Announcing printerd]

Posted May 30, 2012 1:35 UTC (Wed) by dkg (subscriber, #55359) [Link]

Yes, you can certainly use socat with ssh to forward UNIX-domain sockets.

Announcing printerd

Posted May 23, 2012 14:57 UTC (Wed) by Jluis (guest, #28564) [Link] (1 responses)

There has been, and still is, a tool to acces a remote dBus see: http://gabriel.sourceforge.net/howto.html. I remember that it was used by some developers in the openmoko comunity

Announcing printerd

Posted May 24, 2012 0:34 UTC (Thu) by nix (subscriber, #2304) [Link]

Interesting! I'll have a look at that...