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Sudo Settings
2015/11/21
 
Configure Sudo to separate users' duty if some people share privileges.
It's unnecessarry to install sudo manually because it is installed by default even if Minimal Install.
[1] For SUSE Linux, root password is required when using sudo by default settings, so, change it that users can authenticate with their own password when using sudo.
dlp:~ #
visudo
# line 63,64: comment out

#
Defaults targetpw
#
ALL ALL=(ALL) ALL
[2] Transfer root privilege to a user all.
dlp:~ #
visudo
# add to the end: user 'suse' can use all root privilege

suse ALL=(ALL) ALL
# how to write ⇒ destination host=(owner) command
# verify with user "suse"

suse@dlp:~>
/bin/cat /etc/shadow

/bin/cat: /etc/shadow: Permission denied    
# denied normally
suse@dlp:~>
sudo /bin/cat /etc/shadow

suse's password:    
# own password
...
...
uucp:*:16357::::::
wwwrun:*:16357::::::    
# just executed
[3] In addition to the setting [1], set that some commands are not allowed.
dlp:~ #
visudo
# near line 30: add aliase for the kind of shutdown commands

Cmnd_Alias SHUTDOWN = /sbin/halt, /sbin/shutdown, \
/sbin/poweroff, /sbin/reboot, /sbin/init
# add ( commands in aliase 'SHUTDOWN' are not allowed )

suse ALL=(ALL) ALL,
!SHUTDOWN
# verify with user "suse"

suse@dlp:~>
sudo /sbin/shutdown -r now

Password:
Sorry, user suse is not allowed to execute '/sbin/shutdown -r now' as root on dlp.  
# 拒否された
[4] Transfer some commands with root privilege to users in a group.
dlp:~ #
visudo
# near line 30: add aliase for the kind of user management comamnds

Cmnd_Alias USERMGR = /usr/sbin/useradd, /usr/sbin/userdel, /usr/sbin/usermod, \
/usr/bin/passwd
# add to the end

%usermgr ALL=(ALL) USERMGR
dlp:~ #
groupadd usermgr

dlp:~ #
usermod -G usermgr suse

# verify with user "suse"

suse@dlp:~>
sudo /usr/sbin/useradd testuser

suse@dlp:~>    
# done normally

suse@dlp:~>
sudo /usr/bin/passwd testuser

Changing password for user testuser.
New UNIX password:    
# set testuser's password

Retype new UNIX password:
passwd: all authentication tokens updated successfully.
[5] Transfer a command with root privilege to a user.
dlp:~ #
visudo
# add at the end

suse    ALL=(ALL)  /usr/sbin/visudo
cent    ALL=(ALL)  /usr/sbin/useradd, /usr/sbin/userdel, /usr/sbin/usermod, /usr/sbin/passwd
ubuntu  ALL=(ALL)  /usr/bin/vi
# verify with user "suse"

suse@dlp:~>
sudo /sbin/visudo
# possible to open and edit

## Sudoers allows particular users to run various commands as
## the root user, without needing the root password.
##
# verify with user "cent"

cent@dlp:~>
sudo /sbin/userdel -r testuser

cent@dlp:~>    
# done normally
# verify with user "ubuntu"

ubuntu@dlp:~>
sudo /bin/vi /boot/grub2/grub.cfg
# possible to open and edit

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
[6] The logs for sudo are kept in '/var/log/secure', but there are many kind of logs in it. If you'd like to keep only sudo's log in another file, Configure like follows.
dlp:~ #
visudo
# add to the end

Defaults syslog=local1
dlp:~ #
vi /etc/rsyslog.conf
# line 160: add

*.*;mail.none;news.none;local1.none     -/var/log/messages
# line 172: remove "local1"

local0.*                      -/var/log/localmessages
# add to the end

local1.*                       /var/log/sudo.log
dlp:~ #
systemctl restart rsyslog

 
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