[Dovecot] configuration problem.. with passwd

 Hi i was trying to configure dovecot. Under the authentication section i have set the auth_passdb=/etc/passwd auth_user=root auth_userdb=/etc/passwd

But it gives Error in configuration file /etc/dovecot.conf line 398 :missing value which points to auth_passdb=/etc/passwd in the file. Firstly do i need setup some other parameters I want to follow the most simple authentication process. Please advice. thanks