Jespa is a closed-source, pure Java Microsoft Active Directory client. It is being recommended by the JCIFS group as a replacement for the old JCIFS NTLM servlet filter. At the time of writing, Jespa is free to use for up to 25 users -- beyond that you need to purchase a license from IOPLEX.
The JCIFS SSO filter was discontinued since it used a "man-in-the-middle" implementation technique that is not compatible with NTLMv2. See the JCIFS FAQ on this subject.
If you are in a bind and still want to use the old JCIFS SSO filter, configure JCIFS to fall back to NTLMv1 using the system properties:
Also see the properties described in the JCIFS API documentation.