You have a Juniper SSG 520M firewall but you have lost admin password. You don’t have other any user to login then you require reset admin password. You have to take backup because after reset password, it will be factory default and all configurations will wipe out.
Step-1: Connect to firewall through console or serial cable.
Step-2: Login the firewall using serial number as username and password.
Step-3: Then you will be promoted Y/N; if you put Y then firewall will be reset.
Step-4: Login the firewall using following default username and password.
Once it has been reset, set ip address in a physical interface and connect network cable, Now you can login through network.http://10.1.1.10
Password: netscreenNow you can restore old configuration file. If you don’t have backup, you need reconfigure manually.