Problem: SSG5 (SSG 20) doesn’t upgrade via it’s usb port and reports error “USB flash is not existed. Please insert USB first!”

Solution: You need to use a usb flash drive/stick that is 4GB OR SMALLER!  And formatted FAT (aka FAT16).  FAT32 will probably work too (I haven’t tried).

More detail:

If you are on the SSG’s console, you will see the following error if you attempt to use a usb flash device bigger than 4GB:

“Usb disk size is larger than 4G.Mount failed!”

When you use a 4GB or smaller usb flash disk, you will see success:

“usb device (usb) ready.”

Again, this is on the SSG’s console.

Then you can upgrade via usb (put the *unzipped* screenos image in the *root* directory of the FAT usb drive):

ssg5-> save soft from usb ssg5ssg20.6.3.0r21.0 to flash

Then reboot:

ssg5-> reset

SSG5/SSG20 is a legacy Netscreen ScreenOS firewall/router.