Ubuntu – wake-on-lan (wol) a server with full-disk encryption

Ubuntuwake-on-lanzentyal

I have a server installed with zentyal 3.0.2 (based on ubuntu 12.04.2) with full-disk encryption.

While I successfully send the WOL packet and turn on the server, the boot process does not complete since the server disk is encrypted and I need to enter the valid pass phrase before proceeding.

Is there any application that can be used to send the pass phrase?

wol is really useful when we need to manage the server remotely.

Best Answer

To decrypt the boot volume you'll have to use some kind of lights-out management or Intelligent Platform Management Interface (IPMI). This will give you a remote console onto the server so you can type in that passphrase. Common examples of this are the ILO on HP servers or the DRAC on Dell servers.

If you're sending a WOL packet, I really doubt there's a lot of extra overhead in opening up a management console to type in the passphrase. With that said, this is an opportunity to revisit why you're doing all of this:

Why are you powering off the server? Servers are designed to stay on all the time, if you have a power constraint or similar you should explore some power saving options that allow you to leave the server running.
Why is the boot volume encrypted? On-disk encryption only really helps if you believe that the entire server will be physically stolen and someone will try to steal the data. Is your data worth stealing? What happens if someone steals it? Shouldn't you store your server in a place that's physically protected under lock and key?
Even if your disk is encrypted, it has to remain decrypted while the system runs. This means that if you get hacked, your on-disk encryption is worthless because the attacker just stole your unencrypted data off the running system.

Please think about why you're solving this problem and what business purpose it serves.

Related Solutions

Linux – How to get ethtool wake-on-lan setting to “stick”

You could use /etc/rc.local or some system boot scripts, but this wouldn't be the best way to do it. On startup your network interfaces are configured, sure, but there are other times when your network interfaces may be brought up or down and you will need this executed during those times.

You want to edit /etc/network/interfaces:

You should have a line like:

iface eth0 inet static

Underneath that, indented further, you want to create a post-up and post-down commands e.g.

iface eth0 inet static
    post-up /usr/sbin/ethtool -s eth0 wol g
    post-down /usr/sbin/ethtool -s eth0 wol g

Obviously, replace eth0 with the relevant interface if different.

See interfaces(5) for more information on post-up and post-down commands

man 5 interfaces

Wifi – How to boot up Windows Server 2003 remotely using Wake On LAN

1) Wake up on LAN is a feature of the BIOS and network card:

Wake-on-LAN support is implemented on the motherboard (BIOS) of a computer and the network interface (firmware), and is consequently not dependent on the operating system (and NIC drivers) running on the hardware, although the operating system can sometimes control the Wake-on-LAN behaviour.

Source

2) The connection type of the machine sending the wake up signal shouldn't matter. As long as it is fully connected to the network they should be able to send the signal.

In case the computer being woken is communicating via Wi-Fi, the wake-up-packet can be sent via Wireless Multimedia Extensions (WMM)

3) There are tools to help you do this, though configuring the Server should just be a matter of setting up the BIOS correctly. The wake up is done by what Wikipedia calls a "Magic Packet" that contains the IP address of the server to be woken and the "wake-up" packet. This can be sent by any script/program that can access the network:

wolcmd 001122334455 10.0.0.2 255.255.255.255 7

(from the same Wikipedia page).

4) WOL does work over the Internet.

Best Answer

Related Solutions

Linux – How to get ethtool wake-on-lan setting to “stick”

Wifi – How to boot up Windows Server 2003 remotely using Wake On LAN

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