[FreeNX-kNX] cups to cups print problem

[Alastair Johnson]

First of all thanks to the nomachine and freenx developers for an impressive 
piece of code. Now if I can just get this printing sorted out...

I can't get CUPS to CUPS printing working without manually forwarding a port 
on the server to 631 on the client, and manually configuring the printer in 
the printer control panel within the remote session. From what I've read in 
the release notes this _should_ now work without the manual steps, though all 
the recent remote printing details in the list archives seem to discuss 
Windows clients. I've read Kurt's 'Simple printing with FreeNX' doc to, 
though this seems to describe things as they were rather than as they are 
now. If there's something I've missed then please point me to it.

Am I right in thinking the NX client is setting up a forwarded port for CUPS 
traffic, but that it is protecting it from other server users by requiring 
authentication? From the logs I could see an entry for addprinter, giving a 
port (usually 3000 or 3001 for me). Trying to connect to 
http://localhost:3000 from within the remote session I get a dialog asking 
for username and password, but the username and password I logged in with 
don't work. What should be used here? Configuration details below:

Client:
Gentoo i586
!M NX Client 1.5.0-135 from emerge
HP510 configured in CUPS, verified available to all on this and other subnets 
without authentication (just for testing to make sure this isn't a source of 
problems, and within firewall limitations)
Client configured for unix-kde desktop, ssl encryption of all traffic enabled, 
CUPS printing on port 631 enabled and HP510 selected

Server:
FC3
http://fedoranews.org/contributors/rick_stout/freenx/freenx-0.4.4-1.fdr.0.noarch.rpm
http://fedoranews.org/contributors/rick_stout/freenx/nx-1.5.0-4.FC3.1.i386.rpm
node.conf has ENABLE_KDE_CUPS="1" set
nxnode has been tweaked in cmd_node_addprinter() to force MODEL="deskjet.ppd" 
since I never saw the dialogs nxclient -printer should produce, and to change 
lpadmin to /usr/sbin/lpadmin since this didn't seem to be in the path.

When I connect from the client and go to the 'Printers' section of the KDE 
Control Center I see 'HP510' configured as default printer. The CUPS server 
is shown as localhost:10001 and the printer information shows:
HP510
Type: Local printer
State: Idle (accepting jobs)
Location:
Description: HP510
URI: ipp://localhost:10001/printers/HP510
Device:  ipp://localhost:3001/printers/HP510
Model: HP DeskJet Series CUPS v1.1

Unfortunately this cups server is unable to print, canceling the jobs without 
notification and giving entries like the following in  the error log:
E <timestamp> Unable to convert file 0 to printable format for job 
<job_number>!
I <timestamp> Hint: Do you have ESP Ghostscript installed?
I <timestamp> Hint: Try setting the LogLevel to "debug".

The server's main cups server (localhost:631) was tested by creating a 
forwarded port from 631 on the client to 5001 on the server, then adding a 
printer my510 connecting to ipp://localhost:5001/printers/HP510. This was 
done through the kde gui again, with the printer information identical to the 
above, but for the port numbers (631 not 10001 and 5001 not 3001) and 
produced a test page on the client's printer.

Connecting the kde printer gui to the client's cups server on localhost:5001 
worked fine too.