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In Ubuntu 12.10, at the login screen, I enter my user name and password. It accepts my credentials, the screen clears, and the login screen shows up again asking for my credentials once again. It is a constant loop.

I can, however, login remotely via PuTTY.

I have attempted fixing the issue in recovery mode, to no avail.

The issue started happening after a recent install of Kerberos and reconfiguring Samba to authenticate with the Windows Server 2008 R2 Domain.

I have attempted purging Samba and reinstalling, that did not fix my problem. I am at a loss, and I also am not an IT professional. My boss, wanted to avoid spending money and threw this task upon me.

Here is the portion of my Samba file that deals with the configuration:


## Browsing/Identification ###

# Change this to the workgroup/NT-domain name your Samba server will part of
workgroup = CABLETEST_NEW
#password server = WINDOWSSERVER
wins server =
security = ads
template shell = /bin/bash
winbind use default domain = false
winbind offline logon = false
winbind separator = +
#allow trusted domain = Yes
#deadtime = 10

Any help would be greatly appreciated.

Here is my auth.log:

Sep  4 12:02:49 LINUXSERVER su[2609]: pam_unix(su:auth): authentication failure;    logname=elliot uid=1000 euid=0 tty=/dev/pts/0 ruser=elliot rhost=  user=root
Sep  4 12:02:49 LINUXSERVER su[2609]: pam_winbind(su:auth): getting password (0x00000388)
Sep  4 12:02:49 LINUXSERVER su[2609]: pam_winbind(su:auth): pam_get_item returned a password
Sep  4 12:02:49 LINUXSERVER su[2609]: pam_winbind(su:auth): request wbcLogonUser failed: WBC_ERR_AUTH_ERROR, PAM error: PAM_USER_UNKNOWN (10), NTSTATUS: NT_STATUS_NO_SUCH_USER, Error message was: No such user
Sep  4 12:02:52 LINUXSERVER su[2609]: pam_authenticate: Authentication failure
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migrated from serverfault.com Sep 6 '13 at 3:09

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Have you checked the x11 server log? Usually when it loops like that it isn't an authentication issue (you've already authenticated successfully), but is instead because of the user's profile has an error or the window manager couldn't start, etc. –  Andrew Cho Sep 5 '13 at 14:46
@AndrewCho: I have checked for the x11 log. It does not exist. Seeing that it is purely a command interface, there would be no need for a Window Manager? –  shi3re Sep 5 '13 at 14:55
@user1827233, My mistake, I improperly assumed Ubuntu->X11 login screen. It is still very likely to be profile misconfiguration. If you have the ability, try creating a new user and logging in on the console with that account. If it does not generate the same loop, it is specific to the user profile you're trying. In any case, the authentication logs (/var/log/auth.log) would let you know if there was a problem with authentication. Syslog might also have useful info if it is happening before the user's profile is pulled in. –  Andrew Cho Sep 5 '13 at 15:02
@AndrewCho: I have put a few lines from my auth.log file. There is definitely an authentication error of some sorts. Could there be a potential confusion between Ubuntu Server and Windows Server 2008? –  shi3re Sep 5 '13 at 17:54
Is your server supposed to be authenticating off the AD domain or using shadow passwords (/etc/{passwd,shadow}) for authentication? Is it intentional that your pam configuration files (/etc/pam.d files) be changed to authenticate against winbind for system login? –  Andrew Cho Sep 5 '13 at 22:59

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