libgksu authentication mode set to su

upon further research I think the issue might be with gksu.

Everytime I try to use gksu with my admin password, the action I am trying fails

not sure what I did, but installed a few more packages and rebooted and now things are working. I was able to install a deb file using gdebi and install the virtualbox expansion pack. Was able to execute a gksu operation as well (gksu thuanr) and it opened up fine after I entered my password.

Could you please give exact details on how you used gdebi? The log file /var/log/auth.log may be helpful in gathering more information about this. However, be aware that there may be sensitive information in it like the IP address from which you ssh'ed into the machine. Thanks in advance.

I have the same issue, upgraded from 12.10 and cannot install .deb packages with gdebi. This is what happened, I wanted to install Virtual Box with the .deb package that they have on their site. I used the file manager to get to the .deb file and right clicked on it and selected Open With > Gdebi Package Installer. GDebi opens fine but when trying to install it asks for a password and the admin password won't work. This worked fine when I was on 12.10. I managed to install the package doing the same thing but instead of choosing GDebi, I chose Open With Ubuntu Software Center, and it installs fine with that. I haven't been able to install the virtual box extensions though because it asks for an administrative password.

Fixed by opening gksu-properties on a terminal and selecting "sudo" instead of "su"

great jdavila.. well done that was it... working.. 13.04

thank you

Running /usr/bin/gsku-properties in a terminal one is presented with a gui dialog where they can choose different authentication modes. There are two choices, sudo or su. It'd be helpful to know which choice is selected for people having an issue. Thanks in advance!

The value chosen is stored as a gonf key in /apps/gksu/sudo-mode.

And I meant /usr/bin/gksu-properties earlier.

Neither xubuntu nor lubuntu -default-settings seem to change either of these at least in 13.04.

This article may helpful for some people as it generally deals with authentication issues:

http://askubuntu.com/questions/176337/installed-perfectly-but-password-not-working-for-login-or-authentication

[Expired for gdebi (Ubuntu) because there has been no activity for 60 days.]

I just experienced this bug on Ubuntu 13.04 amd-64 desktop. The following appeared in /var/log/auth.log after attempting to install a VirtualBox extension package:

Jul 30 12:47:54 will-desktop su[9696]: pam_unix(su:auth): authentication failure; logname= uid=1000 euid=0 tty=/dev/pts/5 ruser=will rhost= user=root
Jul 30 12:47:56 will-desktop su[9696]: pam_authenticate: Authentication failure
Jul 30 12:47:56 will-desktop su[9696]: FAILED su for root by will
Jul 30 12:47:56 will-desktop su[9696]: - /dev/pts/5 will:root

Running gksu-properties, it seems that the 'authentication mode' is originally set to 'su', which does not work when there is no root administrator password set (default + strongly recommended for Ubuntu desktop installation, see https://help.ubuntu.com/community/RootSudo). Switching the option in gksu-properties to 'sudo' and then using the logged-in user's password fixed the issue.

It seems this default should really be fixed in Ubuntu's default install, but application developers could also call 'gksudo' instead of 'gksu', which seems to use 'sudo' properly regardless of the gksu-properties setting.

Will, thanks for the information. I've now been able to recreate this.

On a freshly installed raring system update-alternatives --display libgksu-gconf-defaults returns:

libgksu-gconf-defaults - auto mode
  link currently points to /usr/share/libgksu/debian/gconf-defaults.libgksu-sudo
...

However running gconftool-2 -g /apps/gksu/sudo-mode returns 'false'. So we are effectively not using sudo-mode for libgksu. I haven't been able to determine what is settings sudo-mode to false though.

This is confusing, when I run "gconftool-2 -g /apps/gksu/sudo-mode" in a fresh lxc container I get "false". When I manually run "sh -x /var/lib/dpkg/info/libgksu2-0.postinst configure" I get true afterwards.

Manually running 'sudo update-gconf-defaults' on my test system resolved the issue, so it seems like it is not getting run during an install.

Looking at update-gconf-defaults we see:

if 'DPKG_RUNNING_VERSION' in os.environ and options.signal:
    # This is what happens when we are called in an obsolete postinst/prerm script
    # Do nothing, it will be done in the trigger
    sys.exit(0)

So when the postinst script calls update-gconf-defaults it just exits.

and the trigger doesn't fire because the package doesn't ship any files in /usr/share/gconf/defaults, it instead installs a symlink with update-alternatives. So the package postinst needs to explicitly call dpkg-trigger to get the gconf trigger to fire.

This doesn't absolutely need to be fixed in Quantal as libgksu was installed by default and subsequently the gconf defaults were updated as other packages were installed.

This bug was fixed in the package libgksu - 2.0.13~pre1-6ubuntu3

---------------
libgksu (2.0.13~pre1-6ubuntu3) saucy; urgency=low

  * debian/libgksu2-0.postinst: Remove call to update-gconf-defaults and use
    dpkg-trigger to set sudo-mode (LP: #1173013)
 -- Brian Murray <email address hidden> Mon, 19 Aug 2013 14:20:16 -0700

Hello David, or anyone else affected,

Accepted libgksu into raring-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/libgksu/2.0.13~pre1-6ubuntu2.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

I installed libgksu2-0 version 2.0.13~pre1-6ubuntu2.1 from raring-proposed and confirm that the authentication mode was set to sudo. I verified this using gksu-properties and gconftool-2 -g /apps/gksu/sudo-mode.

This bug was fixed in the package libgksu - 2.0.13~pre1-6ubuntu2.1

---------------
libgksu (2.0.13~pre1-6ubuntu2.1) raring-proposed; urgency=low

  * debian/libgksu2-0.postinst: Remove call to update-gconf-defaults and use
    dpkg-trigger to set sudo-mode (LP: #1173013)
 -- Brian Murray <email address hidden> Mon, 19 Aug 2013 15:41:16 -0700

The verification of this Stable Release Update has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regresssions.