ipmitool

Out-of-band server management via IPMI. Serial-over-LAN console, remote power control, BMC network config, and hardware sensors.

Serial Over LAN (SOL)

Activate SOL — remote serial console over the network

ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> sol activate

Deactivate SOL — cleanly close the session

ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> sol deactivate

Escape SOL session — when stuck

~.

SOL requires serial console enabled on the server. If you connect but see no output, the OS may not have a serial getty running. See Serial Console Setup below.

Check SOL configuration

ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> sol info

Serial Console Setup (on the server)

Enable serial getty — provides login prompt over SOL

# Try ttyS0 first (most common), then ttyS1 if no output
sudo systemctl enable --now serial-getty@ttyS0.service

Find which serial port IPMI uses

dmesg | grep ttyS

Configure GRUB for serial output

# Add to /etc/default/grub:
GRUB_TERMINAL="console serial"
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=1 --word=8 --parity=no --stop=1"

# Rebuild GRUB
sudo grub2-mkconfig -o /boot/grub2/grub.cfg

BMC Network Configuration

Set static BMC/IPMI IP address

sudo ipmitool lan set 1 ipsrc static
sudo ipmitool lan set 1 ipaddr 10.50.1.200
sudo ipmitool lan set 1 netmask 255.255.255.0
sudo ipmitool lan set 1 defgw ipaddr 10.50.1.1

Show current BMC network config

sudo ipmitool lan print 1

Power Control

Power on/off/cycle — remote power button

ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> power on
ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> power off
ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> power cycle
ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> power status

Hardware Sensors

Read all sensor values — temperature, voltage, fan speed

ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> sensor list

Read system event log

ipmitool -I lanplus -H 10.50.1.200 -U ADMIN -P <password> sel list

Why IPMI Matters

IPMI provides out-of-band management — it works even when:

The OS is crashed or hung
Emergency/rescue mode is active
Network config is broken (bridge VLAN change killed SSH)
The server is powered off

During INC-2026-04-13-001, IPMI saved the recovery twice:

kvm-01 stuck in emergency mode — IPMI HTML console to edit fstab
kvm-02 lost all connectivity after bridge PVID change — IPMI console to revert

Rule: Configure IPMI before you need it. Have it ready before making any network changes over SSH.