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3- Download the file from Juniper website -to- the Device : Configuration Tab >>> Software Distribution
1- gather information from Juniper download website ( release version, size, MD5 checksum )
https://www.juniper.net/support/downloads/?p=srx300#sw
2- Create a image library( just a pointer where the image reside ) : Configuration Tab >> Software Library sub-Tab
3- Download the file from Juniper website -to- the Device : Configuration Tab >>> Software Distribution
