• The machine cannot reach the authentication server or directory server that
contains that user's information.
• There may be problems with the X Window System authenticating this particular
user, especially if the user's home has been used with another Linux distribution
prior to installing the current one.
To locate the cause of the login failures with network authentication, proceed as
follows:
1 Check whether the user remembered their password correctly before you
start debugging the whole authentication mechanism.
2 Determine the directory server which the machine relies on for authentication
and make sure that it is up and running and properly communicating with the
other machines.
3 Determine that the user's username and password work on other machines
to make sure that his authentication data exists and is properly distributed.
4 See if another user can log in to the misbehaving machine. If another user
can log in without diculty or if root can log in, log in and examine the /var/
log/messages le. Locate the time stamps that correspond to the login attempts
and determine if PAM has produced any error messages.
5 Try to log in from a console (using [Ctrl] + [Alt] + [F1]). If this is successful,
the problem is not with PAM or the directory server on which the user's home
is hosted, because it is possible to authenticate this user on this machine. Try
to locate any problems with the X Window System or the desktop (GNOME or
KDE). For more information, refer to Section A.2.4.4, “Login Successful but
GNOME Desktop Fails” (page 253) and Section A.2.4.5, “Login Successful but
KDE Desktop Fails” (page 254).
6 If the user's home directory has been used with another Linux distribution,
remove the Xauthority le in the user's home. Use a console login via [Ctrl]
+ [Alt] + [F1] and run rm .Xauthority as this user. This should eliminate X
authentication problems for this user. Try graphical login again.
7 If graphical login still fails, do a console login with [Ctrl] + [Alt] + [F1]. Try to
start an X session on another display—the rst one (:0) is already in use:
startx -- :1
This should bring up a graphical screen and your desktop. If it does not, check
the log les of the X Window System (/var/log/Xorg.
displaynumber
.log) or
the log le for your desktop applications (.xsession-errors in the user's home
directory) for any irregularities.
8 If the desktop could not start because of corrupt conguration les, proceed
with Section A.2.4.4, “Login Successful but GNOME Desktop Fails” (page 253)
or Section A.2.4.5, “Login Successful but KDE Desktop Fails” (page 254).
252 Start-Up
