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KDE Developer's Journals

How Dapper LTS Succeeded To Spoil CUPS Printing (Part Two -- The Live CD)

pipitas's picture

Kubuntu Dapper CD download finished now. Took long enough to complete....

I'm booting one of the spare machines here in the office, a very cheap desktop workstation (Intel P IV 1.80 GHz, 256 MByte RAM, 20 GByte HD) into a full KDE 3.5.2 desktop system right now...

...

Woot! It is giving me the full resolution of the 1280x1024 LCD screen attached to it. It is surprisingly fast and responsive. I would have expected this system to behave rather slow with only 256 MByte of RAM, given that it runs from CD... but it is amazingly responsive! Its look is also very slick. I like it. I'm very pleased on this front.

Other positive items I've to note:

  • The setup of the UnionFS file system seems to be just perfect, as may be seen in the next point
  • I can use "apt-get install" without any hitch to add more software (due my RAM limitations, I restrained it to "apt-get install openssh-server" though)
  • networking is unbearably slooooow; Konqueror seems to wait 10-20 seconds before it even tries to start connecting to any URL I give it (UPDATE: do "echo 'KDE_NO_IPV6=1' >> /etc/environment" to disable IPv6 support and speed up Konqui's networking)
  • The new "System Settings" application is a good step in the right direction; newbie users typically are overwhelmed when one exposes them to all offerings of kcontrol

Things I didn't like too much:

  • No sshd is included; no remote login to the running system possible (think of support to newbies or some such)
  • The local harddisk and its partitions are not shown to the user -- hence, they can not be mounted into the Live system (unless you know the commandline to do so); Dapper developers, have a look at how easy Knoppix makes this step for its users!
  • System Settings --> Hardware --> Keyboard didn't let me select the German keyboard layout; the CD had booted into an US layout (I had not paid attention to select the right one during the initial boot pause) [Yes, I know I should look in Regional & Accessibility -- but does every newbie know this too?]

Now let's look at the Live CD's printing capabilities...

These do indeed "under-perform", to use a modern business management term (or should I use geek language and say "they suck more than a Hoover vacuum cleaner top-of-class model"?).

Executive summary:

  • It is not possible to install a working printer into Dapper running from Live CD
  • It is not possible to print from the Live CD to remote printers shared by other CUPS servers

Don't say these printing features are not possible from a Live CD; just look at Knoppix how to do it! I tried all methods known to mankind to install a printer into the Live CD Dapper. All with the same success:

  • It didn't work via the "KDE Add Printer Wizard"
  • It didn't work via via the "System Settings" application
  • It didn't work via from the commandline with the CUPS "lpadmin" utility
  • It didn't work via the CUPS admin web interface
  • (It did work to add printers by manually creating printers.conf with an editor, copying the PPDs to their designated place and restarting cupsd -- but these printers wouldn't print then)
  • It is not possible to auto-discover remote printers shared by another CUPS server
  • It is not possible to print to remote printers shared by remote CUPS-1.1.23 servers even after printer discovery was enforced

I surely do wonder if the Dapper CUPS packagers have ever tested these functions? All the error messages are very obvious; and any cursory printing test will let you stumble across them:

"KDE Add Printer Wizard" and "System Settings":
Both pop up a dialog saying: "Unable to change printer properties. Error received from manager: client-error-request-value-too-long" (screenshot)
"lpadmin" command:
Returns a message saying: "lpadmin: Request Entity Too Large"
CUPS admin web interface:
Displays a nearly empty page saying in big letters: "413: Request Entity Too Large" (screenshot)

[image:2070 align="right" hspace=4 vspace=4 border=0 width="300" class="showonplanet"]

The failure to install a printer can't be caused by correct drivers being amiss on the CD; these are there, all of them. 67 MByte worth of PPDs (more than 2600 files) from Linuxprinting.org are packed onto the system. They just don't install when setting up a printqueue, and this is indicated by above error messages.

I tried to create various printers, using various drivers, and I all named them "dappertest<N>" (with <N> being just a number).

In all these cases, in fact a printqueue was created. However, it did not associate a driver with it; so the queue remained a "raw" one, which for most common use cases is non-functional (unless you have a PostScript print device, and know how to generate and send PostScript to it). The CUPS web interface reports "Local Raw Printer" in its "Make and Model" field. "lpstat -p" correctly lists the printer names I had assigned; "lpstat -v" lists the printer device URIs I had used; "lpoptions -p dappertest3 -l" tells me "Destination dappertest3 has no PPD file!".

[image:2071 align="right" hspace=4 vspace=4 border=0 width="300" class="showonplanet"]

But printing to the "raw" queues doesn't work either (though I know how to do it...). Sigh!

I did one last check: create a "good" printers.conf file with an editor, place the PPDs into the appropriate sub directory, restart CUPS and see if that works. Well, it didn't. CUPS listed the new printers just fine (commandline, web interface and kprinter all display them; CUPS listed the printer device URIs completely and correctly (again, commandline, web interface and kprinter); and CUPS also listed the the PPD-derived print options (only commandline and kprinter -- the web interface did not, because not only have Dapper packagers deprived their users from doing administration tasks via the CUPS web, but their instructions about how to restore that behaviour do not work either...).

I can only assume that Ubuntu CUPS packagers' patching of the pristine CUPS sources and configuration (amongst other things, they're changing file permissions and ownerships) has introduced some weird bugs. Because I know for a fact, that all these things do work with a CUPS that is compiled from pristine 1.2.0 sources. (Yes, there is a 1.2.1 release out since 2 weeks, and it fixed about 30 different issues -- but none which are related to what I described here).

All this does not bode well for the next test: installing Kubuntu onto a harddisk and look how good or bad its CUPS printing support is. I'll do that tomorrow and report back then. Stay tuned.

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healyp's picture

KDE_NO_IPV6

Thanks for the tip!

Ever since I installed breezy badger on my m/c at home konqueror had been really slow to respond. Once I added your KDE_NO_IPV6 suggestion to /etc/environments things are /much/ improved.

Thanks again.

xanthine's picture

sshd

> No sshd is included

That's overall a good thing for security reasons. If the user sets his computer up with a weak password (e.g. using the same password as the username), then it will get cracked very quickly via brute force (search for "authentication failure" in /var/log/auth.log to see just how often a typical computer has common username + password combinations tested via ssh).

pipitas's picture

"no sshd a good thing" ??

OK, xanthine,

in that case it should be an even better thing to not include support for wireless connections, at least not the type that works out of the box.

After all, many publically available access points do not use encryption. Users who connect to their bank account details and/or type in other delicate info should be protected from doing so, no?

Cheers,
Kurt

P.S.: BTW, I didn't say I wanted sshd *running* by default, but I'd like to have it installed, so that I can run it if I want....

xanthine's picture

Convenience / security tradeoff?

Hmm...without numbers I can't be sure, but I imagine it's a tradeoff between security and convenience.

Most users probably wouldn't use ssh for remote support, and so the tradeoff of explaining to a user how to type in "apt-get install sshd", etc is worth it for the security of the majority of users who don't need ssh support.

OTOH, things like wireless support are used by a far larger proportion of users (plus, if it isn't enabled by default, there's no one necessarily to tell the user how to enable it, unlike if the user was talking to a support person). So even if it's insecure in some cases (where the attacker requires physical proximity, unlike with ssh, and wouldn't things like bank details be protected over https?), the risk is worth it.

P.S. Installing sshd but not enabling it sounds like a good idea, but how would the user then enable it? Any method I can think of seems to be about as complex as typing in the install command, which is hardly *that* hard.

manuellópezibáñez's picture

You are welcome to contribute

It would be sad that all this effort you are doing is wasted... I guess you are welcome to join the Ubuntu Printing Team and help them to do the things the Right Way.

zander's picture

obvious question

Just so you don't sound like a slashdot user; can you link to the bugreport on https://launchpad.net ?

munchkinguy's picture

I've already reported it!

I have already reported this bug on Launchpad. Please help fix it. At the time, I believed that it was two seperate bugs, so the reports for "both" can be found at:

https://launchpad.net/distros/ubuntu/+source/cupsys/+bug/45500
and
https://launchpad.net/distros/ubuntu/+source/gnome-cups-manager/+bug/41423

pipitas's picture

5 minutes ago I visited this

5 minutes ago I visited this page:

https://launchpad.net/distros/ubuntu/dapper/+source/cupsys/+bugs

It said: "Bugs in Dapper cupsys [....] There are currently no open bugs."

munchkinguy's picture

Perhaps you were looking for this...

The cupsys bugs are listed at:

https://launchpad.net/distros/ubuntu/+source/cupsys/+bugs/
(there is no "dapper")

pipitas's picture

slashdot user?

Thomas,

not sure what exactly you mean with "sounding like a slashdot user"?

And what "link to the bugreport on...", specifically?

Also, can you tell me what this launchpad thingie is meant to do for me (and you)? It is not obvious to me from visiting the site for a quick look. It requires me to register, and that's not what I currently want to do.

FWIW, after my last blog entry (dealing with "Flight 6" and printing) 2 months ago I got feedback (in mail + on IRC) by several Ubuntu people, promising me that they'll fix what problems I found. However, nothing is fixed; some things now are worse even....

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