Ubuntu – Sudo requires password after adding user to sudoers

passwordpermissionssudouser-management

I have added my user in sudoers file, after a restart ubuntu still requires password to execute command.

Below is my sudoers file.

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

aman    ALL=(ALL:ALL) ALL

Here "aman" is current loggedin user name.

Actually in my ubuntu 16.04 I am facing wifi issue which I am able to resolve using below command but I want to execute this command on startup without prompting for password.

systemctl restart network-manager.serviceroot

I have also tried below command but no sucess, every time I am going to execute command ubuntu prompt me to enter password.

usermod -aG sudo username

UPDATE :- Now below is my sudoers file screen shot

Note:- When I execute whoami command terminal shows "aman"

Below is the image shows me as i am administrator

Best Answer

You should use NOPASSWD option

aman ALL=(ALL) NOPASSWD:ALL

However, I would not recommend it that way, because user aman can execute anything without password. I would only allow the systemctl command to be executed without password like this:

aman     ALL=NOPASSWD:/bin/systemctl

It is safer that way.

Related Solutions

Ubuntu – Sudoers file, enable NOPASSWD for user, all commands

The line you added was overridden. From man sudoers:

When multiple entries match for a user, they are applied in order. Where there are multiple matches, the last match is used (which is not necessarily the most specific match).

In your case nicholsonjf was a member of the group sudo so for him this line applied:

%sudo   ALL=(ALL:ALL) ALL

If you want to override entries in /etc/sudoers just put the new entries after them.

The new entry should look like

myuser ALL=(ALL) NOPASSWD: ALL for a single user, or

%sudo ALL=(ALL) NOPASSWD: ALL for a group.

Ubuntu – Block a command from sudo user

According to sudoers manual:

   It is generally not effective to "subtract" commands from ALL using the
   ’!’ operator.  A user can trivially circumvent this by copying the
   desired command to a different name and then executing that.  For
   example:

       bill        ALL = ALL, !SU, !SHELLS

   Doesn’t really prevent bill from running the commands listed in SU or
   SHELLS since he can simply copy those commands to a different name, or
   use a shell escape from an editor or other program.  Therefore, these
   kind of restrictions should be considered advisory at best (and
   reinforced by policy).

This is why your sudoers policy doesn't work.

If you would like to prevent user to gain root permission and change its password, try this procedure:

Assuming your sudoers contains this directive:

 root    ALL=(ALL:ALL) ALL
 %sudo   ALL=(ALL:ALL) ALL

Assuming your user name is foo, his groups are foo and sudo. groups command output is:
```
foo sudo
```
Remove user foo from sudo group: gpasswd -d foo sudo after this, user foo can not run any command with sudo.
Edit sudoers file. Use this command:
```
sudo visudo -f /etc/sudoers.d/foo
```
Define user foo permission, for example:
```
foo ALL=/usr/bin, !/usr/bin/passwd, !/usr/bin/su
```
This means that user foo may run any commands in the directory /usr/bin/ except passwd and su command. Note: If the user foo wants to change his password, can run passwd command without sudo.
Another example of user foo permission:
```
foo ALL =/usr/bin, /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd root
```
This means that user foo may run any commands in the directory /usr/bin/ and is allowed to change anyone’s password except for root on ALL machines.

You can define groups of command by define Cmnd_Aliases and create "levels of permissions". You can found useful examples in EXAMPLE section of sudoers manual, and here is a useful link about how to use sudoers.

Best Answer

Related Solutions

Ubuntu – Sudoers file, enable NOPASSWD for user, all commands

Ubuntu – Block a command from sudo user

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