Ubiquiti cfg partition
Ubiquiti WA devices contain a cfg mtd patition. It uses a proprietary format and holds device configuration as well as the contents of /var/etc/persistent
Layout
The config partition can store multiple configurations.
Each configuration starts with a 24 byte header:
| Ubiquiti cfg header | ||||||
|---|---|---|---|---|---|---|
| name | magic | length | crc | unknown | id | padding |
| offset | 0x00 | 0x04 | 0x08 | 0x0c | 0x10 | 0x14 |
| length | 0x04 | 0x04 | 0x04 | 0x04 | 0x04 | 0x04 |
| usage | header magic | payload length | crc32 | unknown | config id | |
| value | 0x12345678 | 0x00000000 | ||||
id
Seen values: 0x01000000, 0x02000000 Seems to identify the config currently in use, config with 0x01000000 is backup config
crc
CRC32 of zlib deflated textual device config
unknown
The two most significant bytes seem to be always 0.
| Seen values (lower 16 bit) | ||
|---|---|---|
| hex | binary | |
| device a | 0x2831 | 0b0010100111101000 |
| device b | 0x29e8 | 0b0010101011010100 |
| device c | 0x2ad4 | 0b0010100000110001 |
Payload format
The payload is zlib compressed and consists of the concatenation of textual device config and the tared and gziped folder /var/etc/persistent