Sudo

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Configure sudo

[1]

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".

# sudo su -

Transfer root privilege to a user all.

[root@dlp ~]# visudo

# 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 ~]# visudo

# 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 )

centALL=(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 ~]# visudo

# 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 ~]# visudo

# 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 ~]# visudo

# 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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