Examining AVM FRITZ!Box firmware

$ mkdir ~/Firmware; cd ~/Firmware
$ wget https://download.avm.de/fritzbox/fritzbox-7590/other/fritz.os/FRITZ.Box_7590-07.13.image

$ sudo apt install binwalk

$ ls
FRITZ.Box_7590-07.13.image
$ binwalk --signature --term FRITZ.Box_7590-07.13.image 

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
0             0x0             POSIX tar archive (GNU)


$ tar xvf FRITZ.Box_7590-07.13.image
./var/
./var/install
./var/regelex
./var/tmp/
./var/tmp/kernel.image
./var/tmp/filesystem.image
./var/info.txt
./var/content
./var/version
./var/chksum
./var/urladerupdate
./var/signature


$ cd tmp/
$ binwalk --signature --term kernel.image 

DECIMAL       HEXADECIMAL     DESCRIPTION
------------------------------------------------------------------------------------------------------------------------------------------------------
4753479       0x488847        LZMA compressed data, properties: 0x5B, dictionary size: 0 bytes, uncompressed size: 2152784640 bytes


ron@laptop-dell:~/Desktop/Firmware/var/tmp$ binwalk --signature --term filesystem.image 

DECIMAL       HEXADECIMAL     DESCRIPTION
------------------------------------------------------------------------------------------------------------------------------------------------------
0             0x0             Squashfs filesystem, big endian, version 4.0, compression:xz, size: 24002361 bytes, 3836 inodes, blocksize: 65536
                              bytes, created: 1970-10-05 19:19:21

$ binwalk --extract --quiet filesystem.image
WARNING: Extractor.execute failed to run external extractor 'sasquatch -p 1 -le -d 'squashfs-root' '%e'': [Errno 2] No such file or directory: 'sasquatch': 'sasquatch', 'sasquatch -p 1 -le -d 'squashfs-root' '%e'' might not be installed correctly

WARNING: Extractor.execute failed to run external extractor 'sasquatch -p 1 -be -d 'squashfs-root' '%e'': [Errno 2] No such file or directory: 'sasquatch': 'sasquatch', 'sasquatch -p 1 -be -d 'squashfs-root' '%e'' might not be installed correctly

$ git clone https://github.com/devttys0/sasquatch
$ cd sasquatch
$ ./build.sh
..

$ mkdir -p /usr/local/bin
$ cp sasquatch /usr/local/bin

$ binwalk --extract --quiet filesystem.image 
$ ls
filesystem.image  _filesystem.image-0.extracted  _filesystem.image.extracted  kernel.image