Baseboard management controller
A baseboard management controller ( BMC ) is a specialized microcontroller that is embedded on the motherboard of many computer systems - especially servers . In the Intelligent Platform Management Interface (IPMI), the BMC manages the interface between the software and the system management or the hardware.
The BMC receives data on system parameters such as temperature , speed of rotation of the fans , operating system status etc. via the corresponding sensors.The BMC outputs these sensor values and can send alarm messages to the system administrator via the network if parameters leave a set interval and thus suspect a system malfunction to let. The administrator can then access the computer remotely and, for example, restart it if the operating system has crashed.
The physical interfaces to the BMC are SMBus , a console via the serial interface , address and data lines and the Intelligent Platform Management Bus (IPMB), through which the BMC can process IPMI requests from other management controllers in the system.
The BMC communicates with the BMC Management Utility (BMU) on a remote client via IPMI protocols. The BMU is typically a command line program and usually requires a password to access the BMC. The connection to the BMC via a network can also be encrypted. In the case of a serial data connection, no encryption is used because this connection is already assumed to be secure.
Due to the closed structure of BMCs, questions about their security have remained largely unanswered to this day.
See also
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- Zhuo, Haihong, Yin, Jianwen, & Rao, Anil V .: Remote Management with the Baseboard Management Controller in Eighth-Generation Dell PowerEdge Servers (PDF; 253 kB)
- Bruce Schneier: The Eavesdropping System in Your Computer