Debian is currently in the process of dropping the
direct LDAP support in sudo, in favor of sssd. From sudo's NEWS.Debian.gz:
> In practice, there are few installations that use sudo-ldap. Most installations that use LDAP as a directory service and sudo have now opted for sssd, sssd-ldap and libsss-sudo.
> The Debian sudo team recommends the use of libsss-sudo for new installations and the migration of existing installations from sudo-ldap to libsss-sudo and sssd.