FreeIPMI provides in-band and out-of-band IPMI software based on the IPMI
v1.5/2.0 specification. The IPMI specification defines a set of interfaces for
platform management and is implemented by a number vendors for system
management. The features of IPMI that most users will be interested in are
sensor monitoring, system event monitoring, power control, and serial-over-LAN
(SOL). The FreeIPMI tools and libraries should provide users with the ability to
access and utilize these and many other features. A number of useful features
for large HPC or cluster environments have also been implemented into FreeIPMI.

See also: https://www.gnu.org/software/freeipmi/