Disable reboot using Ctrl-Alt-Del Keys in RHEL / CentOS


In Linux , It’s a security concern for us  to allow anyone  to reboot the server using  Ctrl-Alt-Del keys. It is always recommended in production boxes that one should disable reboot using Ctrl-Alt-Del keys.

In this article we will discuss how can we disable reboot via above keys in RHEL & CentOS

For RHEL 5.X & CentOS 5.X

To prevent the init process from handling Ctrl-Alt-Del, edit the file  ‘/etc/inittab‘ comment the line which begins with ‘ca::ctrlaltdel:‘  as shown below :

[root@localhost ~]# cat /etc/inittab
 # Trap CTRL-ALT-DELETE
 #ca::ctrlaltdel:/sbin/shutdown -t3 -r now

We can also modify the line ‘ca::ctrlaltdel:’  to generate logs , if anybody try to reboot the server using the keys ,

[root@localhost ~]# cat /etc/inittab
 # Trap CTRL-ALT-DELETE
 ca::ctrlaltdel:/bin/logger -p authpriv.warning -t init "Console-invoked Ctrl-Alt-Del was ignored"

For RHEL6.X & CentOS 6.X

In RHEL 6.X / CentOS 6.X , reboot using the keys are handled by the file ‘/etc/init/control-alt-delete.conf‘.

Step:1 Before making the changes , first take the backup using below command

[root@localhost ~]# cp -v /etc/init/control-alt-delete.conf /etc/init/control-alt-delete.override

Step:2 Edit the file , replacing the ‘exec /sbin/shutdown’ line with the following, which will simply generate a log entry each time Ctrl-Alt-Del is pressed:

[root@localhost ~]# cat /etc/init/control-alt-delete.conf
 exec /usr/bin/logger -p authpriv.notice -t init "Ctrl-Alt-Del was pressed and ignored"

For RHEL 7.x & CentOS 7.x

Run either of the beneath command from the console to disable reboot using ‘CTRL+ALT+DELETE’ keys in RHEL 7.x and CentOS 7.x

[root@localhost ~]# ln -sf /dev/null /etc/systemd/system/ctrl-alt-del.target

OR

[root@localhost ~]# systemctl mask ctrl-alt-del.target

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