Libntlm implement the Microsoft NTLM authentication protocol.

Libntlm is licensed under the GNU Lesser General Public License version 2.1 or (at your option) any later version.

References for the NTLM protocol are:

The old libntlm (note lower case) was a library that implement Microsoft's NTLM authentication. However, the packaging of libntlm lacked certain things, such as having build problems, lacking shared library support, lacking autoconf macro for use in other applications, lacking pkg-config support, and more. So this page distributes an improved version of the library; called Libntlm (note upper case L to differentiate it from the original libntlm). Compared to the original releases, the current version has been entirely re-written and only shares the same function interfaces.

Projects using Libntlm include GNU SASL.

What's new


The releases are distributed from release directory.

Recent releases are signed with an OpenPGP key with fingerprint B1D2BD1375BECB784CF4F8C4D73CF638C53C06BE.

Older releases are signed with an OpenPGP key with fingerprint B565716F or an OpenPGP key with fingerprint 54265E8C.


The Libntlm project page at GitLab provides an issue tracker and more.

A mailing list where Libntlm users may help each other exists, and you can reach it by sending e-mail to Archives of the mailing list discussions, and an interface to manage subscriptions, is available through the World Wide Web at


There is a Savannah Libntlm project page and a GitLab Libntlm project page.

You may check out the sources as follows:

$ git clone

Simon Josefsson