This tool can be used to change the version information of .chk image files, as used by many Netgear routers.
Some of these devices reject firmware files, whose version is lower than the currently installed one, preventing downgrades, or in some cases flashing of custom firmware.
Usage is fairly straightforward. The version information can be displayed using
$ patchchk EX3700-V1.0.0.22_1.0.17.chk
Board ID : U12H319T00_NETGEAR
Region : WW
Version : 1.0.0.22_1.0.17
Sizes
- Header : 58
- Kernel : 5622416
- Root FS : 0
Checksums
- Header : 0xf8fc0a5a
- Kernel : 0x292d8a81
- Root FS : 0x00000000
- Image : 0x292d8a81
To change the version to 1.0.0.22_1.0.18, simply run
$ patchchk -v 1.0.0.22_1.0.18 EX3700-V1.0.0.22_1.0.17.chk
Version : 1.0.0.22_1.0.18
Checksum: 0xf9270a5b
Now verify using:
$ patchchk EX3700-V1.0.0.22_1.0.17.chk Board ID : U12H319T00_NETGEAR Region : WW Version : 1.0.0.22_1.0.18 Sizes - Header : 58 - Kernel : 5622416 - Root FS : 0 Checksums - Header : 0xf9270a5b - Kernel : 0x292d8a81 - Root FS : 0x00000000 - Image : 0x292d8a81