Why same user has different password and system properties over SSH and GUI login (Debian)?

it flag

I am using a VM on Google Cloud Platform. Once created it can be accessed through SSH through the GCP web GUI. When I access through SSH, I can use sudo to perform privileged actions. When I access through a GUI method such as Chrome Desktop or VNC, I do not have sudo privilege. However I get my same username through whoami in either case.

I am confused because I have some assumptions:

  • whoami indicates the current user by their name.
  • There is only one user for a given name on the whole system, and vice versa.
  • sudo applies to the current user (the same one as whoami)
  • A user's authentication and sudo properties are the same across the whole system.

If these are true I don't understand how there is different sudo behavior when I log in different ways.

Update 3:

I ran sudo usermod -aG sudo username and after rebooting the user has sudo privileges everywhere. Nothing changed in the sudoers files. I didn't think to check the groups file before making the change.

I think everything is fine now from a practical aspect. I still don't understand how the same user can have different sudo privileges in different places.

Update 2:

In /etc/sudoers the non-commented lines (and directive) are:

Defaults        env_reset
Defaults        mail_badpass
Defaults        secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
root    ALL=(ALL:ALL) ALL
%sudo   ALL=(ALL:ALL) ALL
#includedir /etc/sudoers.d

in sudoers.d is google_sudoers containing

%google-sudoers ALL=(ALL:ALL) NOPASSWD:ALL

OS version: Debian 10 (buster) Linux 4.19.0-17-cloud-amd64


Unfortunately maybe it could be caused by some features Google have added relating to a google-sudoers group.

Relevant logs from /var/log/auth.log

gpasswd[2309]: user user_me added by root to group google-sudoers

Succcessful sudo:

sudo: user_me : TTY=pts/2 ; PWD=/home/user_me ; USER=root ; COMMAND=/usr/bin/echo test
sudo: pam_unix(sudo:session): session opened for user root by user_me(uid=0)
sudo: pam_unix(sudo:session): session closed for user root

Unsuccessful sudo:

sudo: user_me : user NOT in sudoers ; TTY=pts/0 ; PWD=/home/user_me ; USER=root ; COMMAND=/usr/bin/echo test

I still am not sure how the behavior can be different for the same user.

John Hanley avatar
cn flag
Try adding your username o the sudo group: **sudo usermod -aG sudo username**. If that solves the problem compare the differences.
Goli Nikitha avatar
ng flag
Need of some additional information to troubleshoot this issue : 1.Run 'tail -f /var/log/auth.log' and let each user logon to see if there are any issues and also Run "id -a" and provide the output. 2.Can you confirm if the VM is using OSLOGIN and the image used by the VM is a google provided one?

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