Installing IPMI and setting a password and ip address is pretty easy. IPMI lets you remotely access your machine just like you are in front of it. It is only supported by machines with an IPMI interface.
First if you are using Proxmox the following is a good idea:
nano /etc/apt/sources.list.d/pve-enterprise.list #comment out line nano /etc/apt/sources.list #add the following deb http://download.proxmox.com/debian wheezy pve-no-subscription
Then to install IPMI tools do the following on Ubuntu, Debian, Proxmox, etc
apt-get update apt-get -y install ipmitool freeipmi-tools modprobe ipmi_si type=kcs ports=0xCA2 regspacings=1 modprobe ipmi_devintf modprobe ipmi_msghandler modprobe ipmi_poweroff modprobe ipmi_watchdog
FreeBSD is even simpler:
pkg install ipmitool kldload ipmi
Now use the following lines to set the network information, a password, and print the results
ipmitool -I open lan set 1 ipsrc static ipmitool -I open lan set 1 ipaddr 18.104.22.168 ipmitool -I open lan set 1 netmask 255.255.255.0 ipmitool -I open lan set 1 defgw ipaddr 22.214.171.124 ipmitool -I open lan set 1 access on ipmitool -I open user set password 2 your password ipmitool lan print
Now you should be able to access your machine by visiting https://126.96.36.199 and logging in with root and your password. Of course replace that ip with you down ip, and network settings.