[CentOS] CentOS-5.2 su -l is failing

James B. Byrne byrnejb at harte-lyne.ca
Wed Jan 14 17:13:27 UTC 2009

I am encountering an odd problem with su.  Up until quite recently I was
able to connect to one of my servers (CentOS-5.2) via ssh as an ordinary
user and then, from the shell, perform an $ su -l to obtain root access. 
Now when I try to do this I see the following:

$ su -l
su: incorrect password

If, instead of I ssh to this machine as the root user ($ ssh -l root host)
and enter exactly the same password from the same keyboard then I log in
successfully as root.  I have made no conscious changes to the target
system configuration files and I know that the first method, logging in as
a normal user and then su -l to root, was working just a few days ago. 
Review of the man and info pages does not enlighten me as to what might be
wrong.  The log file says this:

Jan 14 12:00:22 inet01 sshd[15433]: Accepted password for myuser from
x.x.x.x port 53458 ssh2
Jan 14 12:00:22 inet01 sshd[15433]: pam_unix(sshd:session): session opened
for user myuser by (uid=0)
Jan 14 12:00:32 inet01 su: pam_unix(su-l:auth): authentication failure;
logname=myuser uid=500 euid=500 tty=pts/8 ruser=myuser rhost=  user=root

Any ideas as to what might be happening here and how I might fix it?


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James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
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