Let's assume that pppd returns following message:
rcvd [CHAP Challenge id=0x1 <12345>, name = ""]
and password is "test". What string should I use to calculate MD5 hash for CHAP Response? [https://www.cisco.com/c/en/us/support/docs/wan/point-to-point-protocol-ppp/25647-understanding-ppp-chap.html] - here there is general description. But I still miss the details... I know that I should concatenate challenge, ID and password, but what is the correct order of concatenating those strings? Should I convert password from ASCII to hex before calculating hash?