Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 04-08-2006 Installation Manual page 929

them but then does not behave properly (fails to start the graphic desktop, produces
errors, drops to a command line, etc.).
52.4.1 Valid Username and Password
Combinations Fail
This usually occurs when the system is configured to use network authentication or
directory services and, for some reason, is unable to retrieve results from its configured
servers. The root user, as the only local user, is the only user that can still log in to
these machines. The following are some common reasons why a machine might appear
functional but be unable to process logins correctly:
• The network is not working. For further directions on this, turn to
"Network Problems"
• DNS is not working at the moment (which prevents GNOME or KDE from working
and the system from making validated requests to secure servers). One indication
that this is the case is that the machine takes an extremely long time to respond to
any action. Find more information about this topic in
Problems" (page 935).
• If the system is configured to use Kerberos, the system's local time might have
drifted past the accepted variance with the Kerberos server time (this is typically
300 seconds). If NTP (network time protocol) is not working properly or local NTP
servers are not working, Kerberos authentication ceases to function because it de-
pends on common clock synchronization across the network.
• The system's authentication configuration is misconfigured. Check the PAM confi-
guration files involved for any typographical errors or misordering of directives.
For additional background information about PAM and the syntax of the configu-
ration files involved, refer to
In all cases that do not involve external network problems, the solution is to reboot the
system into single-user mode and repair the configuration before booting again into
operating mode and attempting to log in again. To boot into single-user mode:
1 Reboot the system. The boot screen appears, offering a prompt.
2 Enter 1 at the boot prompt to make the system boot into single-user mode.
(page 935).
Chapter 28, Authentication with PAM
Section 52.5, "Network
Common Problems and Their Solutions
Section 52.5,
(page 513).
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