A flaw was reported [1] in FreeIPA 4.0/4.1 where users could log in using only the OTP value. This arose because ipapwd_authentication() successfully determined that an empty password was invalid, but 389 itself would see this as an anonymous bind. This will be fixed in the next release [2]. As support for OTP is not available in earlier versions, only FreeIPA >= 4.0 is affected. [1] https://fedorahosted.org/freeipa/ticket/4690 [2] https://www.redhat.com/archives/freeipa-devel/2014-November/msg00068.html Acknowledgements: Red Hat would like to thank FreeIPA upstream for reporting this issue. Statement: This issue did not affect the versions of IPA as shipped with Red Hat Enterprise Linux 5, 6, or 7 as they did not include support for OTP.