Solution to can't become root with "su root" -
(pam_authenticate: Authentication failure) solution
I've stumbled upon a weird problem after my linux recovery. With
normal user credentials I was not able to properly execute the
su root
After some investigation in
/var/log/auth.log I found the
following error:
Mar 8 19:12:38 noah login[2956]: pam_unix(login:session):
session opened for user hipo by LOGIN(uid=0)
Mar 8 19:13:14 noah unix_chkpwd[3442]: check pass; user
unknown
Mar 8 19:13:24 noah unix_chkpwd[3452]: check pass; user
unknown
Mar 8 19:13:24 noah unix_chkpwd[3452]: password check failed for
user (root)
Mar 8 19:13:24 noah su[3441]: pam_unix(su:auth): authentication
failure; logname=hipo uid=1000 euid=1000 tty=/dev/tty2 ruser=hipo
rhost= user=root
Mar 8 19:13:26 noah su[3441]: pam_authenticate: Authentication
failure
Mar 8 19:13:26 noah su[3441]: FAILED su for root by
hipo
On linuxforums website I've found some people complaining about the
same issue as mine. Somebody in the forums pointed out that the
issue is directly caused by the
/etc/pam.d/su pam
configuration file.
Logically I've checked which debian package does this file belongs
to in order to reinstall the package with the command:
debian:~# dpkg -S /etc/pam.d/su
login: /etc/pam.d/su debian:~#
Next I reinstalled the
login package with:
debian:~# apt-get install --reinstall
login
Now after the reinstall of the login deb was completed the issues
with su root from normal user account are gone.