CRC update failed

```
What steps will reproduce the problem?
1. extract the firmware
2. make some (minor) modification
3. build new firmware

What is the expected output?
build succesfull

What do you see instead?
Firmware Mod Kit (build) 0.99, (c)2011-2013 Craig Heffner, Jeremy Collake

Preparing tools ...
Building new squashfs file system... (this may take several minutes!)
Squahfs block size is 64 Kb
Parallel mksquashfs: Using 4 processors
Creating big endian 3.0 filesystem on
/fmk/working_directory/new-filesystem.squashfs, block size 65536.
[===============================================================================
======] 1180/1180 100%
Exportable Big endian filesystem, data block size 65536, compressed data,
compressed metadata, compressed fragments, duplicates are removed
Filesystem size 7819.97 Kbytes (7.64 Mbytes)
26.85% of uncompressed filesystem size (29120.62 Kbytes)
Inode table size 9435 bytes (9.21 Kbytes)
24.11% of uncompressed inode table size (39128 bytes)
Directory table size 11416 bytes (11.15 Kbytes)
51.21% of uncompressed directory table size (22293 bytes)
Number of duplicate files found 13
Number of inodes 1282
Number of files 838
Number of fragments 95
Number of symbolic links 167
Number of device nodes 198
Number of fifo nodes 1
Number of socket nodes 0
Number of directories 78
Number of uids 1
root (0)
Number of gids 0
Remaining free bytes in firmware image: 1105635
Processing 0 header(s) from /fmk/working_directory/new-firmware.bin...
CRC update failed.

Firmware header not supported; firmware checksums may be incorrect.
New firmware image has been saved to: /fmk/working_directory/new-firmware.bin

What version of the product are you using? On what operating system?
Firmware Mod Kit (build) 0.99 on Ubuntu 12.04.3 LTS (64Bit)

Please provide any additional information below.
Firmware of Netgear DGND3800B

Download link:
http://downloadcenter.netgear.com/de/Disclaimer.aspx?redirecturl=http://netgeard
ownload.registria.com/single_page_registration?product[sku]=dgnd3800b&download_u
rl=http://www.downloads.netgear.com/files/GDC/DGND3800B/DGND3800B-V3.0.0.8_3.0.8
.zip

PS:
couldn't upload the firmware itself ("Issue attachment storage quota exceeded.")

Is there any possibillity to find out which header is used in this firmware?

Thanks...

```

Original issue reported on code.google.com by `DanielL...@googlemail.com` on 10 Jan 2014 at 9:30

Start by reproducing the build with the Netgear DGND3800B firmware and inspect the output around “Processing 0 header(s)” and “CRC update failed.” The missing firmware attachment and absent project file or test references make the header format difficult to investigate; done means the header is recognized and the CRC update succeeds.

Written by the indexing model from the issue text.