Out-of-band (OOB) management means controlling a server independently of its operating system — via a dedicated processor on the motherboard called the BMC (Baseboard Management Controller). The BMC has its own NIC, its own firmware, and its own IP. You can power a server on, read temperatures, and access a console whether or not the host OS is running, hung, or even installed.
Used for: bare-metal provisioning, remote recovery, hardware monitoring, firmware updates, automated power management.
Standards
Two main protocols, one old and one new:
| IPMI | Redfish | |
|---|---|---|
| Protocol | Binary, UDP 623 | HTTPS / JSON (REST) |
| Era | 1998– | 2015– |
| Scripting | ipmitool | curl, Python, any HTTP client |
| Security | Weak (known CVEs) | TLS + token auth |
| Availability | Universal | Modern hardware (roughly post-2015) |
- IPMI — the established standard; ipmitool, SoL, sensor readings, security considerations
- Redfish — the modern replacement; REST API, curl and Python examples, firmware updates
Vendor implementations
Most vendors ship their own BMC firmware on top of these standards:
| Vendor | Product | Supports |
|---|---|---|
| Dell | iDRAC | IPMI + Redfish (iDRAC 8+) |
| HP / HPE | iLO | IPMI + Redfish (iLO 4+) |
| Sun / Oracle | ILOM | IPMI 2.0, web UI |
| Supermicro | BMC | IPMI + Redfish (X11+) |
| Lenovo | XClarity / IMM | IPMI + Redfish |
| HP BladeSystem | Onboard Administrator | Enclosure-level; individual blades use iLO |
Related
- Hardware provisioning — PXE boot, bare-metal provisioning tools