PAM Offline Authentication

Offline Authentication using winbindd

In order to enable offline authentication configure Samba to use winbind in nsswitch and for PAM (Authenticating Domain Users Using PAM)

Then make sure smb.conf contains:

"winbind offline logon = yes"

If you are using a Debian based distro there is a bug regarding gencache.tdb, which has been placed in the lock directory /run/samba. This means that it is removed at reboot and hence, winbind offline logon will not work. Until Bug #14618 is fixed, the workaround is to place lock directory = /var/cache/samba in your smb.conf.

Enabling offline authentication in pam_winbind

First of all, make sure that you can login using PAM and your windows credentials, e.g. using ssh:

ssh YOURDOM\\youruser@localhost

You cannot continue if login via PAM (pam_winbind) is not working.

Now, pam_winbind needs to set the offline flag as well, you can do so by either

• adding "cached_login = yes" to /etc/security/pam_winbind.conf. That file should look like this:

#
# pam_winbind configuration file
#
# /etc/security/pam_winbind.conf
#
[global]
# request a cached login if possible
# (needs "winbind offline logon = yes" in smb.conf)
cached_login = yes

This will enable offline ability globally for all applications using PAM. If you want to have more fine grained control about services that use pam_winbind's offline mode then you can do so by

• adding the "cached_login" option into individual pam-configuration files (usualy below /etc/pam.d/$SERVICE)

Testing offline authentication

Start winbindd, authenticate successfully at least once while winbind is online

/etc/init.d/winbind start

 wbinfo -K YOURDOM\\youruser%password

Now you can switch winbindd to offline mode by hand (for testing) with the smbcontrol command.

smbcontrol winbind offline

If you now repeat the command

wbinfo -K YOURDOM\\youruser%password

You should get

user_flgs: LOGON_CACHED_ACCOUNT

in the output.

Your system is now prepared to use pam_winbind while offline. Please try to login to your localhost, e.g. using ssh

ssh YOURDOM\\youruser@localhost

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