To secure the GRUB boot loader and to prevent unauthorized changes to the SLX device at boot time, access to these settings must be password protected. Use the GRUB Configuration mode of the SLX-OS to enforce this.
Password protection of the GRUB Bootloader menu is disabled by default. It must explicitly be enabled.
SLX #configure terminal
SLX (config)#
SLX (config)# grub
SLX (config-grub)#
SLX (config-config)# enable
SLX (config-config)#
You will be able to configure the username and password.
SLX (config-grub)# username testUser password ********
SLX (config-grub)#
The SLX device is now secured from unauthorized changes made by a user who has console access during boot time.

Note
This setting will not be applicable till the SLX device is rebooted.