CentOS 7
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Configure sudo
2014/07/08
 
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] Transfer root privilege to a user all.
[root@dlp ~]#
# add at the last line: user 'cent' can use all root privilege

cent    ALL=(ALL)       ALL
# how to write ⇒ destination host=(owner) command
# make sure with the user 'cent'

[cent@dlp ~]$
/usr/bin/cat /etc/shadow

cat: /etc/shadow: Permission denied
# denied normally
[cent@dlp ~]$
sudo /usr/bin/cat /etc/shadow

[sudo] password for cent:
# own password

daemon:*:16231:0:99999:7:::
adm:*:16231:0:99999:7:::
lp:*:16231:0:99999:7:::
...
...
# just executed
[2] In addition to the setting [1], set that some commands are not allowed.
[root@dlp ~]#
# near line 49: 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 )

cent
ALL=(ALL)
ALL,
!SHUTDOWN
# make sure with the user 'cent'

[cent@dlp ~]$
sudo /sbin/shutdown -r now

Sorry, user cent is not allowed to execute '/sbin/shutdown -r now' as root on dlp.srv.world.  
# denied normally
[3] Transfer some commands with root privilege to users in a group.
[root@dlp ~]#
# near line 51: 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 at the last line

%usermgr ALL=(ALL) USERMGR
[root@dlp ~]#
groupadd usermgr

[root@dlp ~]#
usermod -G usermgr cent

# make sure with the user 'cent'

[cent@dlp ~]$
sudo /usr/sbin/useradd testuser

[cent@dlp ~]$
# done normally

[cent@dlp ~]$
sudo /usr/bin/passwd testuser

Changing password for user testuser.
New UNIX password:
Retype new UNIX password:
passwd: all authentication tokens updated successfully.
[4] Transfer a command with root privilege to a user.
[root@dlp ~]#
# add at the last line

cent    ALL=(ALL) /usr/sbin/visudo
fedora  ALL=(ALL) /usr/sbin/useradd, /usr/sbin/userdel, /usr/sbin/usermod, /usr/bin/passwd
ubuntu  ALL=(ALL) /bin/vi
# make sure with the user 'cent'

[cent@dlp ~]$
sudo /usr/sbin/visudo
# possible to open and edit

## Sudoers allows particular users to run various commands as
## the root user, without needing the root password.
##
# make sure with the user 'fedora'

[fedora@dlp ~]$
sudo /usr/sbin/userdel -r testuser

[fedora@dlp ~]$
# done normally
# make sure with the user 'ubuntu'

[ubuntu@dlp ~]$
sudo /bin/vi /boot/grub/grub.conf
# 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
[5] The logs for sudo are kept in '/var/log/secure', but there are many kind of logs in it. So if you'd like to keep only sudo's log in a file, Set like follows.
[root@dlp ~]#
# add at the last line

Defaults syslog=local1
[root@dlp ~]#
vi /etc/rsyslog.conf
# line 54: add

*.info;mail.none;authpriv.none;cron.none
;local1.none
  /var/log/messages
# add the line, too

local1.*                                                /var/log/sudo.log

[root@dlp ~]#
systemctl restart rsyslog

 
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