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[[Com desbloquejar arrel LUKS per SSH|Català]] - [[Como desbloquear raiz LUKS por SSH|Castellano]] - [[How to unlock LUKS root via SSH|English]]
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'''Introduction:''' This is a simple guide to give access to the net, to introduce the passphrase (password) in the boot of a system already encrypted including the root. In this way is not a requirement to go in person to write it with the keyboard.

'''Notes:'''
* Tested with Debian GNU/Linux 7 (wheezy), but the method should work with older versions and other GNU distributions with Linux.
* It's important to consider that, having the kernel with the decrypter in a non-encrypted partition, is a weak point. The most secure method is to have ALL the hard disk encrypted, and then boot in person with an external memory (such as /boot in a pendrive) and, when having unlocked the system, take that memory with the software intact in our hands.

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== Prepare the remote LUKS unlocking ==
==== From the encrypted system ====

* Install the software for the SSH service and Shell commands interpreter:
 apt-get install dropbear busybox

* Configure the net to the kernel boot stage, setting this variable at the file '''/etc/default/grub'''
 GRUB_CMDLINE_LINUX="ip=192.168.1.33::192.168.1.1:255.255.255.0::eth0:none"
(Example for an IP address ''192.168.1.33'', gateway ''192.168.1.1'' and net device ''eth0'')

* Update boot manager with the new data for the kernel:
 update-grub

* Copy the special entry certificate to the remote computer, from which you will ask for unlocking:
 scp -P 22 /etc/initramfs-tools/root/.ssh/initramfs_rsa RemoteUser@RemoteComputer:/home/RemoteUser/encrypted.example.net_initramfs-rsa
(Example with ''RemoteUser'' of the IP ''RemoteComputer'' and labelling the server as ''encrypted.example.net'')

==== In the remote system ====
(computer from where you want to send the unlocking command)

* (optional) For security, move the certificate to the superuser profile (root):
 mkdir -p /root/.ssh
 mv ~/*_initramfs-rsa /root/.ssh/

* Instruction to give (with the example data) when the encrypted system waits for the passphrase (large line):
 ssh -o "UserKnownHostsFile=/root/.ssh/known_hosts.initramfs" -i "/root/.ssh/encrypted.example.net_initramfs-rsa" root@encrypted.example.net "echo -ne \"1234\" >/lib/cryptsetup/passfifo ; ip addr flush dev eth0 &"
(Example with password 1234, and that deconfigures the net of the encrypted system to not interferes in the normal system)

== Other sources ==
* [https://www.kernel.org/doc/Documentation/filesystems/nfs/nfsroot.txt Kernel command line] (values for the network configuration)