[X2go-User] [X2go-Dev] x2go printing follow up

Mike Gabriel mike.gabriel at das-netzwerkteam.de
Sun Aug 14 19:13:18 CEST 2011


Hi Ted,

On Mo 08 Aug 2011 18:04:18 CEST Ted Barnes wrote:

> We are experimenting with X2go (very cool), but having a devil of a  
> time getting printing to work.  This request for help is keying off  
> of posts by John Sullivan and Mario Oroz (thanks so much for those,  
> guys, e.g.,  see tread  
> http://www.mail-archive.com/x2go-user@lists.berlios.de/msg00104.html  
> and  
> http://www.mail-archive.com/x2go-user@lists.berlios.de/msg00115.html). We  
> are having pretty much the same problem as described there.  We are  
> assuming that X2go printing in general can be made "to work" and  
> that this is a matter of something we are doing wrong (maybe  
> starting with the install?), some necessary "tweaks", etc.
>

To make sure you use latest software, please use these sources for  
installation of the server-side of X2go:

Debian+Ubuntu:
http://wiki.x2go.org/nightly-built_packages_debian_ubuntu

Furtheron for initial debugging, please use x2goclient on Debian or  
Ubuntu to eradicate some not-so-generic Windows problems.

Please install the x2goclient from our nightly builds as well.

Nightly builds are for debugging+testing, not for production setups, though!

> We'd like to post this on the developer's list too to see if that's helpful.
>
> We're hoping to get a number of questions answered, and have  
> provided what may be "too much" description below:
>
> Questions:
>
> Q:  Did we miss something during the setup and installation process?

I will comment your description about setup and installation below, so  
please read the answers to this question there.

The latest general infos are found in our wiki:

   http://wiki.x2go.org

> Q:  Our server does not have a /root/.x2go/ssh/.x2oprint/id_dsa"  
> directory or id_dsa file - do these need to get created by hand?  In  
> fact, our server does not have an "id_dsa" file anywhere on the  
> machine.  If we need to add this, how does one do so (i.e., using  
> the normal ssh key creation process)?  We have some other dsa files,  
> but not one with the specific name id_dsa (i.e., can we use one of  
> the existing ones in /etc/ssh?).

These RSA/DSA files are part of SSH pub/priv authentication and can be  
created with the ssh-keygen tool. Refer to its man page for further  
info.

> Q:  We assume X2goprint and cups-x2go perl scripts are part of this  
> picture.  We don't believe they are being called by the printing  
> process - how would we tell?  If they are necessary but not getting  
> called, thoughts as to why they are not getting invoked when we  
> print and how to fix this?

If you refer to x2goprint as separate X2go package then you are  
definitely using (very) old code.

Unfortunately, the www.x2go.org site and our wiki.x2go.org pages to  
give ambiguous info, this should be fixed and brought in sync ASAP  
(ping at Heinz!!!).

The x2goprint script has become part of the x2goserver package and has  
undergone some changes since then. Please make sure you use the  
nightly build packages for testing+debugging for now (this is a  
recommendation that is valid today, in the future we will bump  
sub-releases in shorter intervals, the x2goserver esp. is very due for  
such a nano release... Sorry for delays on this).

> Q:  In testing (where we simulate what we imagine the printing  
> process to be by doing each step manually) when we issue the .ready  
> command, why does that only seems to work sometimes as judged by the  
> x2go print client popping on the XP side?  Does that tell us  
> something?

Good question. If the latest code does not solve your issues, please  
send the .ready file's content.

> Q:  Should printing be putting jobs in "/" (is that normal)?  Does

NO! You use old server-side packages. Upgrade to the nighly builds.

> the x2goprint script know what to grab based on job#s?  We assume  
> this all should work with multiple users and the x2goscript  
> identifies which jobs to grab and put them individual user spool  
> queues.

Yes, this does work with latest code.

> Q:  To work, should x2goprinting pass the print file from the server  
> through the ssh connection to the client?  Is this in part an "ssh  
> passing the file" problem?  We can connect through putty from the  
> client to the server, and assume we have the keys correct because we  
> can connect from XP to the Ubuntu server via x2go in the first  
> place.  Back to the lack of an id_dsa file?  Again, we're not sure  
> that printing is invoking the right scripts to begin with.

The print job files are stored on the client via SSHFS. The SSHFS file  
sharing uses a temporary pub/priv key pair, so for this mechanism it  
is not relevant if you can SSH to and from the server. The SSHFS mount  
is issued by the server and connects to the client (via a SSH tunnel).

> Q:  Assuming we get this working, we also assume that on the  
> Ghostview/Ghostscript side we shouldn't be having to put the name of  
> the file in the command line, nor actually having to use the command  
> line.  I.e., there is an option there to print that refers to  
> whatever default printer we have set on the XP machine, but  
> currently nothing happens if we use that particular option instead  
> of the command line.

Yes, this should be so. Please test this with a Linux x2goclient  
first. If this works then check with the Windows x2goclient and report  
experienced differences.

> Q:  Should we be using Posgress instead of SQLite?  We are assuming  
> that SQLite is fine until we want to deal with load balancing.

If you want to use:

  o many X2go servers (clustering)
  o restrictive X2go server access based on posix accounts/groups
  -> PostgreSQL

  o one X2go server
  o access for any non-system posix User (everyone who can use SSH)
  -> SQLite

> DESCRIPTION
>
> We are connecting from XP machines using x2goclient to Ubuntu Server  
> 9.10 (connecting is pretty consistent, a few issues now and then but

For testing, please use a Linux client. The latest X2go code is only  
available for Ubuntu >=10.04. For older Ubuntu versions you should be  
able to either

   o backport X2go from X2go Git
   o use the server-side packages for Debian lenny (no nightly builds, though):
     http://wiki.x2go.org/adding_the_x2go_repository_debian

> all in all it works well) over Comcast or Fios connection (DSL too  
> slow).  We are using the X2go with SQLite, cups-x2togo and  
> x2goprint; we have not installed any of the optional "bindings"  
> packages.  We used visudo to add the line "x2goprint All=(ALL)  
> NOPASSWD:  /usr/bin/x2goprint", and added an "x2goprinter" user by  
> hand (that action also created an "x2goprinter" group to which we  
> added our test user accounts).

user=groupname='x2goprint', not 'x2goprinter'!!!

> We have tried uncommenting the settings to activate them in  
> "/etc/cups/cups-x2go.conf" (even though we understand these settings  
> to be used only for a separate cups server) with no change.  As  
> noted above, our server does not have an id_dsa file and while we  
> suspect that as being part of the problem we would have assumed that  
> file would be created as part of the install pocess.

With latest X2go code, printing works out of the box (to my experience).

> On the server, we have a minimal "Ubuntu Desktop" installed so we  
> can use Firefox to browse from the server.
>
> We have GSview 4.9 and Ghostscript 9.02 installed on the XP clients.

Is this needed for x2goclient??? I do not think so... The Ghostscript  
stuff is needed on the client side... However, a PDF viewer will be  
helpful on the Windows client. For testing though: use a Linux machine  
as a client.

> We are trying to print to an older HP Laserjet 4000 shared out on  
> local XP machine (this 2nd machine is not one connecting to the  
> Ubuntu server, no X2go on it, no Ghostview or Ghostscript) and  
> another HP color laser that is a network device.  All printing  
> behavior is the same regardless of which printer we try.

Should work.

> We are hoping outlining the following will help describe what we  
> think is going on, and possible not working:
>
> 1)  On the 9.10 Ubunu server, we installed X2go printing.  If we go  
> to System->Administration->Printing, we can see a  
> "Generic-Cups-X2go-Printer" and it is active.  Its properties  
> include a URI of "cups-x2go:/".   On the same Printer Configuration  
> window, if we press Server->Connect the resulting Cups server is  
> "/var/run/cups/cups.sock".  We are using a 64 bit machine, and can  
> find two instances of the "cups-x2go" and maybe this is part of the  
> problem (one is is /usr/lib64/cups/backend, the other in  
> usr/lib/cups/backend)?

AFAIK /usr/lib64 is a symlink to /usr/lib. So no worries necessary  
about this. The only thing you should make sure is to have these  
permissions set on the cups-x2go backend:

   -rwx------ root root /usr/lib/cups/backend/cups-x2go

This permission setting marks the backend in a way that CUPS knows it  
has to start it with root privileges. Otherwise it is started with  
user privileges and that will fail in this context.

> 2)  If we print from the server, we briefly see a job get created  
> both on the top (right) panel and if we are watching in the Print  
> Configuration window.  Jobs are stored in "/" and stay there until  
> we delete or move them with names that follow the syntax  
> "jobname-username-cupsjob#".  Their permissions are root as owner,  
> lp as group, and no access for users.

-> An old version of x2goprint did this...

> For each print file, there is another cups file of some sort stored  
> in "var/spool/cups" with names like "c00052".  This describes what  
> occurs consistently.  The jobs get "printed" but nothing happens on  
> the windows client side or on the printer.

-> Upgrade the server-side to x2goserver from nightly builds (on an  
Ubuntu >=10.04 machine).

> 3)  [...]

Looking forward to your follow up after you have upgraded X2go (and  
reported as the new versions you use for testing).

Greets,
Mike

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