PAM_USER or PAM_RUSER??

[Max Liccardo <mliccardo.c@mail.tim.it>]

just a dubt:
Should a pam module authenticate PAM_RUSER or PAM_USER?? a lot of
applications don't set PAM_RUSER, on the other side I think that at
least should be PAM_RUSER=PAM_USER....
max