I was put in a situation to bring Juniper Firewall to factory default settings.
Firewall Model: Juniper ISG 1000
Note: By default settings of Juniper Firewall, recovery settings are enabled. Some admins might have disabled it by unset admin device-reset
Step 1: Execute "set admin device-reset" command
Step 2: Execure "reset" command
Say "Yes" to confirm saving the configuration and restarting
Step 3: After the image is loaded in the firewall, at login prompt, type the serial number as user name. At password prompt, type the serial number again. The following message appears
!!! Lost Password Reset !!! You have initiated a command to reset the device to factory defaults, clearing all current configuration and settings. Would you like to continue? y/[n]
Press Y in the screen
!! Reconfirm Lost Password Reset !! If you continue, the entire configuration of the device will be erased. In addition, a permanent counter will be incremented to signify that this device has been reset. This is your last chance to cancel this command. If you proceed, the device will return to factory default configuration, which is: System IP: 192.168.1.1; username: netscreen; password: netscreen. Would you like to continue? y/[n]
Press Y in the screen to reset the device to factory default settings
Note: Connect to Management Port (Set your IP in 192.168.1.0 segment) and access 192.168.1.1. Use netscreen/netscreen as default password.