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RHEL 5 : Can only log in as root

Posted on 2016-09-14
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Last Modified: 2016-09-21
I rebooted my RHEL5 server today.  After discovering I couldn't remote in using ssh, I checked the console and it appeared the system was in runlevel 1 for some reason.  I rebooted again, watched the boot process and couldn't see anything significant.  I checked the runlevel, set the default runlevel to 3 and rebooted again with no effect.  I can log in to the console as root.  But, I cannot log in as any other existing user.  The login fails with no feedback.  If I try to "su - " to the user, I get a "permission" denied to the user's home directory and a "permission denied" to "/bin/bash".  I have tried to troubleshoot by adding a new user and logging in.  Same effect.

The "runlevel" command yields "N 3" which I am pretty sure means it thinks it is running in level 3 now.

All mounts seem to be OK.  I have rebooted with "-F" to force fsck, no problems.  I can navigate to all mounted volumes and access files on all of them.

I'm stumped.  The system was running and accessible when I rebooted earlier.  It is possible I mucked something up earlier when I was working on something else.  But, I am not sure what that might be.

I have crept around the web and there is rarely any mention of this problem.  When I find something, the suggestion of using "strace" is prevalent (did it, didn't reveal any permission issues that I can tell)  or some version of reinstall OS is deployed.

Anybody have any suggestions?
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Question by:ecsginc
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by:loftyworm
ID: 41798694
I am no *nix guru, but I got strong suspicions that you have rooted :(

Maybe check your root boot files and see if anything is amiss

My 2 cents
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by:Scott Silva
ID: 41798894
Is there any message about damaged initrd or anything? If you have damaged boot files a system will usually drop to a minimal root session if it can get that far...
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by:ecsginc
ID: 41801768
All boot of the errors are permissions issues similar to the su errors.  I am now thinking that somehow some uid, gid or permission got inadvertently change.  At this point I am now keying in on the sticky bit.  Does anyone have a list of standard system directories and or files where the sticky bit needs to be set?
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ecsginc earned 0 total points
ID: 41802028
FYI - I solved my problem.  After scouring permissions and ownership until my eyes bled (all errors in /var/logs/dmesg and /ver/log/messages aligned with permissions issues) I threw a Hail Mary and executed "chmod 755 /".  prior to this it was more of 744.  That did the trick.

I am not sure why or how the permissions got changed (I am suspecting and errant scripting inadvertently executed as su/root with empty environment variables yielding "/" on a chmod operation).

Regardless, if anyone should end up on this thread with their own issues, changing the permissions on the root directory ("/") did the trick for me.
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by:ecsginc
ID: 41808401
I discovered the apparent cause of my original issue.
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by:omarfarid
ID: 41808426
If you have a backup for system taken before issue, then you can restore and you will get the old perms
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