ipmitool - can't find /dev/ipmi0 or /dev/ipmidev/0

You probably need to load the IPMI kernel modules:

modprobe ipmi_devintf
modprobe ipmi_si

You can add these to /etc/modules to have them loaded automatically (just list the module names):

ipmi_devintf
ipmi_si

Do you have the devices loaded ? You can load manually the modules : modprobe ipmi_devintf ; modprobe ipmi_si and check your logs

Just wanted to highlight another minor point: "Make sure you are running with root/admin privileges".

user@host:~$ ipmitool power status
Could not open device at /dev/ipmi0 or /dev/ipmi/0 or /dev/ipmidev/0: No such file or directory

user@host:~$ ls /dev/ipmi*
/dev/ipmi0

user@host:~$ lsmod | grep ipmi
ipmi_devintf           20480  0
ipmi_ssif              24576  0
ipmi_si                57344  0
ipmi_msghandler        49152  3 ipmi_ssif,ipmi_devintf,ipmi_si

user@host:~$ sudo ipmitool power status
[sudo] password for user:
Chassis Power is on

user@host:~$