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Enabling cupsys Web Admin Interface October 13, 2005

Posted by Carthik in administration, ubuntu.

If you are trying to get your printing system going, and search for tips and docs on the web, you will find most of the documentation referring to http://localhost:631 as your cupsys administration interface. However, on Ubuntu, this browser-based administrative interface for cupsys is disabled by default. Here’s how to enable it:

Select “System”->”Administration”->”Users and Groups” from the main menu on your desktop.
Select “Show all users” and/or “Show all groups”.
Add the user “cupsys” to the group “shadow” in the “groups” tab.

Restart cupsys by issuing the command:
$sudo /etc/init.d/cupsys restart

IMPORTANT: I don’t know why the web admin interface was disabled in the first place – so please know that it is best to reverse all that you did once by removing the user cupsys from the shadow group,a nd restarting cupsys, once your work with the interface is done. If anyone knows why the web-browser interface was disabled in Ubuntu, please let me know – a lot searching and reading changelogs led me nowhere :)


1. Tommy - October 14, 2005

I believe it’s turned off for the same reason lots of things in Debian/Ubuntu are never turned on… it’s safer to leave them off unless you need them and know how to configure them properly. As for CUPS, I believe there are several known Denial of Service attack issues with it, so maybe those are lessened when the login doesn’t work. I would probably avoid activating the admin interface UNLESS your LAN is behind some sort of firewall.

If I can remember where I saw a clear explanation of the reasoning, I’ll try to post it here, but the most likely place I would have seen it would be the Ubuntu-users email list / forums.

2. The Power of Mind » Habilitar la interfaz web de CUPS en Ubuntu - November 6, 2005

[...] [ Link original ] [...]

3. Erik - December 1, 2005

Tommy, your comment doesn’t make sense. By default cups is limited to localhost access, and in ubuntu you can still access cups interface, just not do any administration tasks. It even still prompts you for authentication when you try, but never lets you in.

I think it was a poor choice for ubuntu to disable this functionality in cups by default. Why allow access to the interface at all if you are going to try to force users to use more annoying GUI tools to configure printers.

4. Michael - December 25, 2005

I have no idea about this, but my intuition says that this would have been disabled to reduce the security impact of any infiltration of CUPS. If somebody finds a security hole in CUPS, usually he’ll get the privilages that CUPS runs under (a.k.a. cupsys user), which is why usually running daemons under their own underprivilaged users is a good idea. If somebody gains access to the cupsys user which is in group ‘shadow’, then that user can read /etc/shadow and maybe copy it and brute-force the passwords (if any) — meaning s/he could hack your system and completely compromise every user on the system.

Whether there have been any such attacks, I don’t know — and AFAIK, CUPS’ web interface is enabled in Debian. [That said, I've never heard of a 'gnome-cups-manager' package in Debian either, or if it is there, I've never felt the need to use it. Gnome-cups-manager has the feel of other GUI systems' way of setting up printers, which is good if you use gnome and/or you need to use the same printer setup method as e.g. Windows for familliarity, but it doesn't help users of Kubuntu or Xubuntu and the like. *shrugs*]

5. nombre - February 9, 2006

Es una prueba

6. Giacomo - February 10, 2006

I think there’s a better way to achieve the result:
(from http://ubuntuforums.org/showthread.php?t=6145)
3) I edited the /etc/cups/cupsd.config file (you can use gedit or vi) so that the cups web interface would not require a username/password to add the printer. I commented out the two lines in section:

AuthType Basic
AuthClass System

changing them to:

#AuthType Basic
#AuthClass System

4) I then restarted cusp daemon so the changes would take effect:

% sudo /etc/init.d/cupsys restart

7. vn7xmen - February 17, 2006

Dear all
I have followed your guide but cups untill requires the password but not except any password???

8. Hakim - February 21, 2006

Well it is obvious the cupsys web admin interface is disabled due to security issues. The easy way to get into accessing a printer is that you got to give the root account a password do a

sudo /bin/bash – you will get root access
passwd root – you can set the root password

cow you can try accessing the cupsys http://localhost:631, you can use root and password, but then it will tell you to login to System >> Administration >> Printers, you can now install your printer :)

9. Hakim - February 21, 2006

You need to provide the a dummy username and password (anything is ok) to the GUI printer Manager.

10. Vladimir Hernandez - July 28, 2006

Considering that Ubuntu does not have a root password by default, then it would make it complicated for a non-advanced user to go to the whole “set the root password / edit cupsysd / restart daemon/ undo everithing” cycle. Therefore, considering this Desktop distro’s intended target audience, it may have been better to annoy a couple of hackers than hordes of newbies.

11. Alan Yeates - July 30, 2006

It gets even worse in Xubuntu, there is not a hint of how to install a printer! Being that I run Ubuntu on my desktop this was no more than a niggle, but how about everybody else? I thought *Ubuntu was to empower the masses, not to drive them into despair!

12. mokelvey - September 16, 2006

Alan & Vladimir! You said it!
Being an aging newbie – aged by trying to get “normal” things (like printing and networking) going in ububtu – I am convinced that all the hard work that goes into creating something like ubuntu is wasted on many newbies because the path to learning is scattered and unhinged by the very problems you are blogging about here. I am on my 3rd week of trying to get my LAN printer, a Ricoh Aficio 1224 C, printing from my ubuntu-Dapper-driven 17″ Powerbook. Last night, I finaly got it to print a test page after punching the “Detect LAN Printers” button in the printer GUI, and ALL the printers appeared including drivers from two other networked Macs running OS X. Needless to say, the two 1224 printers I had added to the Printers GUI still did not function, but the two that popped up did. I say they functioned – they printed a letter-sized test print. The full capabilities of the printer (up to tabloid size and several different trays) are not still NOT accessible at http://localhost:631/printers/ because I don’t have “don’t have permission to access the resource on this server”. What is THAT all about? Can anyone provide a clue as to how I can open up access to my own printer, which works just fine from Macs and the VM PC I have on my LAN, but NEVER from ubuntu?

13. tyggy - September 29, 2006

http://localhost:631/printers is the local server

Restarting the CUPS Server

Once you have made a change to a configuration file you need to restart the CUPS server by sending it a HUP signal or using the supplied initialization script. The CUPS distributions install the script in the init.d directory with the name cups. The location varies based upon the operating system:

/etc/software/init.d/cups restart ENTER
/etc/rc.d/init.d/cups restart ENTER
/etc/init.d/cups restart ENTER
/sbin/init.d/cups restart ENTER

lppasswd -x root #deletes the root cups user

This allows localhost to reset/set root password

lppasswd -a root

14. Marcel Neves - October 10, 2006

Thanks a lot, I was searching for an answer in the web, and your post solved my problem. Thank you

15. lenchy - October 13, 2006

here’s how i solved the usename /password issue and was able to authenticate and install ! Go to administration > users and grougs> look for the user cupsys , click on properties and change the password to something new, exit, and now use username/ password – cupsys/”new password” when prompted during printer installation. also you may need to add user cupsys to the shadow group and restart cups by :

adduser cupsys shadow
/etc/init.d/cupsys restart

16. helpdeskdan - December 27, 2006

That works, but it’s easier to not mess with the gui at all.

sudo adduser cupsys shadow
sudo passwd cupsys
sudo /etc/init.d/cupsys restart

17. akosh - January 5, 2007

helpdeskdan, Thanks very much!!

18. Phil - February 4, 2007

I am having a problem in that Firefox adds to http://localhost:631 to make it http://www.localhost.com and of course timing out has anyone come across this problem before and knows a solution?

19. Ubuntu - Enabling cups web admin interface « technonerd.wordpress.com - May 3, 2007

[...] Ubuntu – Enabling cups web admin interface http://ubuntu.wordpress.com/2005/10/13/enabling-cupsys-web-admin-interface/ [...]

20. Rachael - July 14, 2007

I had the same issue with using the web interface with it not accepting a password so

All I did was give cupsys a password.

# sudo passwd cupsys

This worked for me.

21. Web Hosting - Ok So Im webmail confused Want to set up school computer network dual boot Ubuntu - XP machines with an Ubuntu fileserver - October 9, 2007
22. bryant - March 27, 2008

I have cups installed then suddenly I cant print. I have HP network printer. I wonder why I dont have this cupsys user. I’m using centOS though. I can access the web interface locally but not remotely using a web browser. The error was “You don’t have permission to access the resource on this server”.

>>windows vista has problems with network printers
Really? I’ve been using MS products since DOS and Windows 95. Printing was way easy. Im using Linux for my Apps and DB only.

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26. yudi irianto - August 10, 2008


I have successfully running cups web interface on my pc. But i can’t reach using http://linuxsrv:631

Does anyone has a suggestion?
Thx in advance

27. nicNULL - August 26, 2008

Add the Allow @LOCAL as done below….

# Restrict access to the admin pages…

Order allow,deny
Allow localhost
Allow @LOCAL


28. nicNULL - August 26, 2008

Add this to your cupsd.conf

Listen :631

29. nicNULL - August 26, 2008

Add this to your cupsd.conf

Listen (ip adr to linuxsrv):631

30. ar-lock - October 22, 2008

system administration printing
server settings
allow remote administration
allow whatever else.
now follow the easy as heck web interface.
cat whatever file | lpr
and it will print :)

31. gary - January 7, 2009

I am using Ubuntu intrepid and most of what is written here seems to be overkill/not apply.
To clarify:
By default cups seems to be setup @SYSTEM which means that you just login to the control panel using any valid local user and bingo you can add a printer or cancel jobs.

If you really must go mucking about in /etc/ then be warned – unless you really know what you are doing or can follow forum posting carefully you could be in trouble.

For any new Ubuntu user reading this.
If you have a local user (example) below then just login to cups using that:
User: myuser
Password: mypassword

The above are ***examples only*** – whatever username and password you created when installing Ubuntu can be used to get into cups also.

32. porno sikiş - September 27, 2010

Dear all
I have followed your guide but cups untill requires the password but not except any password???

33. sex sikiş - September 28, 2010

Considering that Ubuntu does not have a root password by default, then it would make it complicated for a non-advanced user to go to the whole “set the root password / edit cupsysd / restart daemon/ undo everithing” cycle. Therefore, considering this Desktop distro’s intended target audience, it may have been better to annoy a couple of hackers than hordes of newbies.

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