`base' is the base for the search as described in RFC 1779.
`scope' is one of the three symbols `sub', `base' or `one'.
`binddn' is the distinguished name of the user to bind as (in RFC 1779 syntax).
+ `auth' is one of the symbols `simple', `krbv41' or `krbv42'
`passwd' is the password to use for simple authentication.
`deref' is one of the symbols `never', `always', `search' or `find'.
`timelimit' is the timeout limit for the connection in seconds.