Flashing OpenWRT or Freifunk to ALFA Network AP121

The ALFA Network AP121 is an access point that seems to be the reference board for many other routers. Its firmware can be replaced by OpenWRT or Freifunk.

But the official bin-file from contains these files:

• kernel_image
• rootfs_image

Flashing this file is rejected with the message "Firmware file error". To fix it, follow these steps:

mv gluon-ffmd-0.37-alfa-ap121.bin gluon-ffmd-0.37-alfa-ap121.gz
gunzip gluon-ffmd-0.37-alfa-ap121.gz
tar xvf gluon-ffmd-0.37-alfa-ap121.gz
mv kernel_image kernel.image
mv rootfs_image rootfs.image
tar czf gluon-ffmd-0.37-alfa-ap121.bin kernel.image rootfs.image

The now created file gluon-ffmd-0.37-alfa-ap121.bin can be uploaded with the script.