In Linux, It’s a security concern for organization 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 / CentOS 7 / RHEL 8 / CentOS 8
Run either of the beneath command from the console to disable reboot using ‘CTRL+ALT+DELETE’ keys in RHEL 7 / RHEL 8 and CentOS 7 / CentOS 8
[root@localhost ~]# ln -sf /dev/null /etc/systemd/system/ctrl-alt-del.target
OR
[root@localhost ~]# systemctl mask ctrl-alt-del.target
