Sudo trouble cant su anymore

Linux
1

I somehow broke sudo on one of my systems and dont know how to fix it.
I looked with the visudo editor and did not find any change.

I tried fixing it by adding an admin group and adding a user to that group. Didnt resolve the problem either.

Anyone has an idea how to fix it?
All I get now is:

$ su
Password:
su: Authentication failure

Here is the visudo setup.
>
> #
> # This file MUST be edited with the ‘visudo’ command as root.
> #
> # Please consider adding local content in /etc/sudoers.d/ instead of
> # directly modifying this file.
> #
> # See the man page for details on how to write a sudoers file.
> #
> Defaults env_reset
> Defaults mail_badpass
> Defaults secure_path=“/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin”
>
> # Host alias specification
>
> # User alias specification
>
> # Cmnd alias specification
>
> # User privilege specification
> root ALL=(ALL:ALL) ALL
>
> # Members of the admin group may gain root privileges
> %admin ALL=(ALL) ALL
>
> # Allow members of group sudo to execute any command
> %sudo ALL=(ALL:ALL) ALL
>
> # See sudoers(5) for more information on “#include” directives:
>
> #includedir /etc/sudoers.d

I am not a fan of sudo at all and think the linux community was duped into believing it is safer for sysadmins. I disagree., but too many things now depend on it so I have to live with it.

2

su only works if you know root user password. In other words type root user password when you run:

su -

If you are in sudo group, run:

sudo command
sudo id
sudo reboot
3

I know but
If I su from a user account and enter root password I get

$ su
Password:
su: Authentication failure

but I can log into root without trouble using Ctrl Alt F1 e.g.

I dont know how this got messed up.

I cannot su to another user account either.

The culprit seems to have been the “MX User” application. It happened after I added another user with it.

4

It ended up being memory corruption. ECC error in a memory pair on that server.
I noticed it when I rebooted. Real Pesky problem this was.
Can you believe it.

Replaced the memory and this problem disappeared.

Nixcraft, I dont know if you want to delete the thread or if it will be useful for the group. It is your decission.

5

That is okay, someone might find it useful later.