Could somebody be able to explain to me what the various unix_listners do in the Dovecot 2.x configuration (specifically 10-master.conf).

Currently, for postfix to use to deliver mail, I have:

service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0660
    user = postfix
  }
}

and for auth I have:

service auth {
  unix_listener /var/spool/postfix/private/auth {
    mode = 0666
  }

  unix_listener auth-userdb {
    mode = 0666
    user = vmail
  }
}

So what does each one specifically do? Also, does somebody know of a resource that can explain the mode setting?