I've installed package ndiff version 7.31-1. As it depends on Python, I installed version 2.7.13-3. Both from repository.
When I call "ndiff" from bash, the result is:

Could not import the ndiff module: 'No module named ndiff'.
I checked in these directories:
If you installed Ndiff in another directory, you may have to add the
modules directory to the PYTHONPATH environment variable.

ndiff script IS IN /usr/bin

There is some file missing from ndiff package? Or some wrong Python config?

I found no other comments in forums about ndiff running in OpenWRT. There is a better alternative?

Could someone help me? Thanks in advance.