The pam_sotp PAM module offers OTP authentication support.
At the moment, the software is still in the early developmental phase, and its users are advised to be cautious while using it. The program seems to be stable, but there are chances that it could contain severe bugs that pose a risk to the security of your system. Thus, it is advisable to refrain from using pam_sotp on mission-critical systems or production servers until a stable release is published.
However, it appears that the software is reaching a stable phase, and many users have reported using it without any issues across multiple configurations. The project is relatively small, but the developer has some short to medium-term plans in mind to enhance the software's functionality.
The upcoming release of pam_sotp 0.4.0 will introduce various patches and bug fixes aimed at improving performance. The developer plans to maintain the 0.4.x branch until it is stable, and subsequently release a couple of 1.0 release candidates before eventually releasing pam_sotp version 1.0. The developer will continue to maintain the 1.0 branch of the software.
This latest version of pam_sotp 0.4.0 comes packed with enhanced features such as the addition of disable and enable commands to otppasswd. A bug fix was made to address the issue where SGID shadow applications could not authenticate against pam_sotp due to some SUID code remaining in the program.
Version 0.3.3: N/A