IPMI (Intelligent Platform Management Interface) is a hardware-level management standard built into most server-class hardware. It runs on a dedicated processor on the motherboard — the BMC (Baseboard Management Controller) — independently of the host OS. The BMC has its own NIC, its own firmware, and its own IP address. You can power a server on or off, read sensor data, and access a serial console even if the host is completely dead.

Current version is IPMI 2.0, which added encryption and stronger authentication over 1.5.

BMC implementations by vendor

IPMI is the standard; each vendor ships their own BMC firmware on top of it:

Most also expose a web UI and some form of virtual KVM (keyboard/video/mouse over network) in addition to IPMI over LAN.

Network setup

The BMC NIC is usually shared with a host NIC (shared/failover mode) or dedicated (preferred for management). Configure via BIOS/UEFI or the vendor’s setup utility before the OS boots.

Assign a static IP — a BMC on DHCP is workable but inconvenient. Keep BMCs on a dedicated management VLAN if possible; they have historically had security issues and shouldn’t be exposed to general traffic.

ipmitool

The standard CLI for IPMI over LAN. Available in most Linux package repos.

# Power control
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> power status
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> power on
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> power off
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> power cycle
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> power reset

# Sensor readings (temperatures, voltages, fan speeds)
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> sensor list

# System Event Log
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> sel list
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> sel clear

# Serial over LAN (SoL) — console access without KVM
ipmitool -I lanplus -H <bmc-ip> -U <user> -P <pass> sol activate
# Exit SoL: ~.

Use -I lanplus (IPMI 2.0 with encryption) rather than -I lan (IPMI 1.5, unencrypted) where supported.

Serial over LAN (SoL)

SoL forwards the server’s serial port over the IPMI connection — giving you a text console to the host without a KVM or physical access. Requires the host OS to have serial console enabled:

# Add to GRUB_CMDLINE_LINUX in /etc/default/grub
console=tty0 console=ttyS1,115200n8

# Enable serial getty
systemctl enable serial-getty@ttyS1.service

Baud rate must match what’s configured in the BIOS/BMC (typically 115200).

Security

IPMI has a poor security history:

• IPMI 1.5 sends credentials in cleartext
• IPMI 2.0 has had multiple authentication bypass vulnerabilities (RAKP, cipher 0)
• The BMC itself runs independent firmware that may have unpatched CVEs
• Default credentials (admin/admin, ADMIN/ADMIN) are common and widely known

Minimum steps:

• Change default credentials immediately
• Use IPMI 2.0 (lanplus) only
• Disable cipher suite 0: ipmitool -I lanplus ... lan set 1 cipher_privs XxxxxxxxxxxxxxxX
• Isolate BMC network from internet and untrusted hosts — management VLAN with no external exposure
• Keep BMC firmware updated

Related

• Redfish — the modern REST API replacement for IPMI
• Out-of-band management overview
• Hardware provisioning — PXE boot and bare-metal provisioning