====== Ubuntu - Sudo - Configure privileges ======

===== Grant root privilege to a user =====

<code bash>
sudo visudo
</code>


Add to the end to allow testuser all root privileges:

<file bash visudo>
...
testuser    ALL=(ALL:ALL) ALL
</file>

<WRAP info>
Format is:

  [user] [host=(owner)] [command]
</WRAP>

Push [Ctrl + x] key to quit visudo.

----

===== Verify with user testuser =====

</code bash>
testuser@sharewiz:~$ /sbin/reboot

Failed to set wall message, ignoring: Interactive authentication required.
Failed to reboot system via logind: Interactive authentication required.
Failed to open /dev/initctl: Permission denied
Failed to talk to init daemon.
# denied normally
</code>


<code bash>
testuser@sharewiz:~$ sudo /sbin/reboot
</code>

Session terminated, terminating shell...   # run normally

----

===== Restrict some commands =====

Add settings that some commands are not allowed.

<code bash>
sudo visudo
</code>

Add alias for the kind of shutdown commands:

<file bash visudo>
# Cmnd alias specification

Cmnd_Alias SHUTDOWN = /sbin/halt, /sbin/shutdown, \
/sbin/poweroff, /sbin/reboot, /sbin/init, /bin/systemctl 

...

# Add (commands in alias [SHUTDOWN] are not allowed)
testuser    ALL=(ALL:ALL) ALL, !SHUTDOWN
</file>

----

==== Verify ====

With user testuser

<code bash>
sudo /sbin/shutdown -r now
</code>

returns:

<code bash>
Sorry, user testuser  is not allowed to execute '/sbin/shutdown -r now' as root on ubuntu.
</code>

----


===== Grant privilege of some commands to users in a group =====

<code bash>
sudo visudo
</code>

Add aliases for the kind of user management comamnds:

<file bash visudo>
# Cmnd alias specification
Cmnd_Alias USERMGR = /usr/sbin/adduser, /usr/sbin/useradd, /usr/sbin/newusers, \
/usr/sbin/deluser, /usr/sbin/userdel, /usr/sbin/usermod, /usr/bin/passwd 

...

# add to the end
%usermgr ALL=(ALL) USERMGR
</file>

----

==== Test ====

<code bash>
sudo groupadd usermgr
</code>

<code bash>
vi /etc/group
# add a user in this group

usermgr:x:1002:testuser
</code>

----

Verify with user testuser

<code bash>
sudo /usr/sbin/useradd testuser
sudo /usr/bin/passwd testuser

Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
</code>

----


===== Grant privilege of some commands to a user =====

<code bash>
sudo visudo
</code>

Add to the end

<file bash visudo>
...
testuser1    ALL=(ALL:ALL) /usr/sbin/visudo
testuser2    ALL=(ALL:ALL) /usr/sbin/adduser, /usr/sbin/useradd, /usr/sbin/newusers, \
                        /usr/sbin/deluser, /usr/sbin/userdel, /usr/sbin/usermod, /usr/bin/passwd
testuser2    ALL=(ALL:ALL) /usr/bin/vim
</file>

Verify with user testuser1.

<code bash>
sudo /usr/sbin/visudo
# run normally
</code>

----

Sudoers allows particular users to run various commands as the root user, without needing the root password.

Verify with user testuser2

<code bash>
sudo /usr/sbin/userdel -r testuser
</code>

----

Verify with user testuser3

<code bash>
sudo /usr/bin/vim /root/.profile
</code>

~/.profile: executed by Bourne-compatible login shells.


----

===== Logs =====

The logs for sudo are kept in '/var/log/auth.log', but there are many kind of logs in it.

So if you'd like to keep only sudo's log in another file, Set like follows.

<code bash>
sudo visudo
</code>

<file bash visudo>
...
# Add to the end

Defaults syslog=local1
</file>

Edit /etc/rsyslog.d/50-default.conf as root.

<file bash /etc/rsyslog.d/50-default.conf>

# line 8: add

local1.*                        /var/log/sudo.log

auth,authpriv.*;local1.none     /var/log/auth.log
*.*;auth,authpriv.none          -/var/log/syslog
</file>

----

==== Restart rsyslog ====

<code bash>
sudo systemctl restart rsyslog 
</code>