How to extract openwrt firmware?

Installing and Using OpenWrt
1

I have a backup of openwrt firmware, the backup is done via
cat /dev/mtd5 > /tmp/backup.bin

And I want to see the files in it on my linux computer without having to restore the firmware to a router. I have tried firmware mod kit https://github.com/openwrt-stuff/firmware-mod-kit and extracted the firmware with
./extract-firmware.sh backup.bin

but instead of extracting the firmware it gave me 3 files:

header.img
footer.img
rootfs.img

With the file command it gave me the following result:
https://s15.postimg.org/qrmikcvln/Screenshot_-_110617_-_12_58_29.png
How do I extract the firmware to my computer?

2

Just a shot in the dark, have you tried 7zip to open the bin file? Sometimes it does magic.

3

7z doesn't work

4

Another shot in the dark.

http://www.linux-mtd.infradead.org/faq/ubifs.html

1 Like
5

And something else to try: testdisk

6

Tools of choice are

binwalk, dd
of course
xz, lzma, cpio, unsquashfs
and more are also needed.

This is not an easy task,
you must do most of the work by yourself.

1 Like
7

I ran into a similar situation just now, and succeeded using 7-zip to open the full-dumped bin file which is exported from the whole flash chip. 7-zip just gave the whole SquashFS to me.

8

binwalk with -M and -e options

$ binwalk -h

Binwalk v2.1.1
Craig Heffner, http://www.binwalk.org

Usage: binwalk [OPTIONS] [FILE1] [FILE2] [FILE3] ...

Signature Scan Options:
    -B, --signature              Scan target file(s) for common file signatures
    -R, --raw=<str>              Scan target file(s) for the specified sequence of bytes
    -A, --opcodes                Scan target file(s) for common executable opcode signatures
    -m, --magic=<file>           Specify a custom magic file to use
    -b, --dumb                   Disable smart signature keywords
    -I, --invalid                Show results marked as invalid
    -x, --exclude=<str>          Exclude results that match <str>
    -y, --include=<str>          Only show results that match <str>

Extraction Options:
    -e, --extract                Automatically extract known file types
    -D, --dd=<type:ext:cmd>      Extract <type> signatures, give the files an extension of <ext>, and execute <cmd>
    -M, --matryoshka             Recursively scan extracted files
    -d, --depth=<int>            Limit matryoshka recursion depth (default: 8 levels deep)
    -C, --directory=<str>        Extract files/folders to a custom directory (default: current working directory)
    -j, --size=<int>             Limit the size of each extracted file
    -n, --count=<int>            Limit the number of extracted files
    -r, --rm                     Delete carved files after extraction
    -z, --carve                  Carve data from files, but don't execute extraction utilities

Entropy Analysis Options:
    -E, --entropy                Calculate file entropy
    -F, --fast                   Use faster, but less detailed, entropy analysis
    -J, --save                   Save plot as a PNG
    -Q, --nlegend                Omit the legend from the entropy plot graph
    -N, --nplot                  Do not generate an entropy plot graph
    -H, --high=<float>           Set the rising edge entropy trigger threshold (default: 0.95)
    -L, --low=<float>            Set the falling edge entropy trigger threshold (default: 0.85)

Binary Diffing Options:
    -W, --hexdump                Perform a hexdump / diff of a file or files
    -G, --green                  Only show lines containing bytes that are the same among all files
    -i, --red                    Only show lines containing bytes that are different among all files
    -U, --blue                   Only show lines containing bytes that are different among some files
    -w, --terse                  Diff all files, but only display a hex dump of the first file

Raw Compression Options:
    -X, --deflate                Scan for raw deflate compression streams
    -Z, --lzma                   Scan for raw LZMA compression streams
    -P, --partial                Perform a superficial, but faster, scan
    -S, --stop                   Stop after the first result

General Options:
    -l, --length=<int>           Number of bytes to scan
    -o, --offset=<int>           Start scan at this file offset
    -O, --base=<int>             Add a base address to all printed offsets
    -K, --block=<int>            Set file block size
    -g, --swap=<int>             Reverse every n bytes before scanning
    -f, --log=<file>             Log results to file
    -c, --csv                    Log results to file in CSV format
    -t, --term                   Format output to fit the terminal window
    -q, --quiet                  Suppress output to stdout
    -v, --verbose                Enable verbose output
    -h, --help                   Show help output
    -a, --finclude=<str>         Only scan files whose names match this regex
    -p, --fexclude=<str>         Do not scan files whose names match this regex
    -s, --status=<int>           Enable the status server on the specified port
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