IPMI Serial over Lan (SoL) on a Dell PowerEdge
Dell PowerEdge 1950 servers are quite nice to play with. But they have a nice feature that most people don’t seem to use – the built-in “Base Management Controller” (BMC).
Basically it’s a built-in management card that can be controlled locally on the server, via the serial console or remotely over LAN. Besides reading various system information such as temperatures, fan-speeds, eventlogs etc. it supports power switching functions (on/off/reset..) and a really nice thing, Serial over Lan (SoL).
Using this feature you can redirect serial output over the network. If you run some sort of unix on the server that means that you can control everything remotely, including the BIOS screens, RAID setup screens, the bootloader and your console – even if you mess up the OS’s network configuration. When running some other operating system the fun most likely stops after the RAID setup screens 😉
How to get it working
During bootup press CTRL-E on the BMC init prompt. Settings:
IPMI over LAN: On
NIC Selection: Shared
LAN parameters:
IP: Static (assign some IP to the BMC)
VLAN Enable: Off
LAN Alert: Off
LAN Users Configuration:
Account access: Enabled
Account Privilege: Admin
Account Username: root
Password: .. (set some password)
In the BIOS:
Serial Communication: On with console redirection via COM2
External Serial Connector: COM2
Failsafe Speed: 57600
Remote Terminal: ANSI
Redirection after boot: Enabled
Note: Dell servers support serial port sharing, meaning that you have to decide what you want to “see” on the physical serial connector on the back (COM1, COM2, BMC/DRAC). See this pdf for details. The BMC seems to output COM2 over LAN by default.
How to connect remotely
Use ipmitool and the following command (obviously replacing the IP address):
ipmitool -I lanplus -H 192.168.100.5 -U root sol activate
To exit type the ~. sequence.
IPMI supports quite some commands, for example to perform a (hard) system reset use the following:
ipmitool -I lan -H 192.168.100.5 -U root -a chassis power reset
There are some special key mappings active for the serial console. A short summary gets shown on system bootup before the BIOS screen appears. To access function keys (F1 F2..) use CTRL-f 2.
Related:
IPMI on Debian Sarge
IPMI configuration with ipmitool
GNU FreeIPMI
Managing Dell PowerEdge Servers Using IPMItool (pdf)
Kenshi Muto’s backported kernel images (to set up Debian Sarge on newer Dell servers)