Re: su doesn't work "Authentication failure"

paul <google@pcwehle.de> writes:

>

[ . . . ]

> 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 


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