However some information on the web seems to imply that FCC rules no longer allow the modification of the firmware on software based radios.
Looking at the FCC web site, this question is linked to two PDFs:
The second PDF lists the requirements that a software radio operating in 5GHz range (a frequency provided by many WiFi routers) must meet in order to become certified by FCC. On p.2 this document says the following under "Third-Party Access Control":
What prevents third parties from loading non-US versions of the software / firmware on the device?
Describe in detail how the device is protected from "flashing" and the installation of third-party firmware such as DD-WRT.
However all of this documentation is for manufacturers, about their responsibility to block customizations like this. The questions I wanted to ask are from the perspective of the end user:
- is it illegal to install custom firmware on a WiFi router?
- if I have a router with custom firmware from another country, is it illegal to operate it in USA?