npppd_auth_username_for_auth
npppd_auth_username_for_auth(realm1, username, buf1), NULL,
return npppd_auth_username_for_auth(ppp->realm, username,
npppd_auth_username_for_auth(ppp->realm, username, buf0), password,
const char *npppd_auth_username_for_auth (npppd_auth_base *, const char *, char *);