+----------------+ | application: X | +----------------+ / +----------+ +================+ | authentication-[---->--\--] Linux- |--<--| /etc/pam.conf | | + [----<--/--] PAM | |================| |[conversation()][--+ \ | | | X auth .. a.so | +----------------+ | / +-n--n-----+ | X auth .. b.so | | | | __| | | _____/ | service user | A | | |____,-----' | | | V A +----------------+ +------|-----|---------+ -----+------+ +---u-----u----+ | | | | auth.... |--[ a ]--[ b ]--[ c ] +--------------+ | acct.... |--[ b ]--[ d ] +--------------+ | password |--[ b ]--[ c ] +--------------+ | session |--[ e ]--[ c ] +--------------+