Re: su doesn't work "Authentication failure"
paul <google@pcwehle.de> writes:
>
> It is possible to do 'su someuser' from root but it's not possible to
> get back to root then using just 'su' or change from a normal user to
> another user account.
[ . . . ]
> Jan 31 15:44:18 myserver su[27729]: (pam_unix) authentication failure;
> logname= uid=1000 euid=1000 tty=pts/4 ruser=myuser rhost= user=root
The "euid=1000" should read "euid=0": your "su" is running as the
invoking user, so it fails for non-root users. The most likely
explanation is that "/bin/su" doesn't have the setuid flag set, so
that would be the first thing to check. (If the setuid bit *is* set,
the problem may be that your root partition has been mounted with the
"nosuid" mount flag or something.)
If you have a logical explanation for the missing bit, great,
otherwise good security practice would suggest that you give a little
thought before restoring setuid bits on files where it has
mysteriously disappeared. If your version of the "login" package is
the latest official Etch version 1:4.0.18.1-7, then "md5sum /bin/su"
should give:
1381ae1ac77b512258657b096522bb6a /bin/su
If your Etch version matches mine but the md5 doesn't, you might start
to get pretty worried.
--
Kevin Buhr <buhr+debian@asaurus.net>
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