Installer og konfigurer CentOS 7 for å eksternt låse opp LVM på LUKS diskkryptering ved å bruke SSH

LUKS (Linux Unified Key Setup) er et av de forskjellige diskkrypteringsformatene som er tilgjengelige for Linux som er plattformagnostiske. Denne opplæringen vil gi deg rot- og byttepartisjoner inne i et LVM (Linux Volume Manager)-volum inne i en kryptert LUKS-partisjon. Denne opplæringen lar deg også låse opp LUKS-partisjonen eksternt ved å bruke en forenklet SSH-serverdemon ved å bruke et hvilket som helst kompatibelt SSH-klientprogram.

Forutsetninger

• En CentOS 7 x64 Minimal ISO Library-serverforekomst.
• En sudo- bruker.
• SSH offentlige nøkkel(er) .
• Dracut-Crypt-SSH .

Trinn 1: Miljøoppsett

På siden Distribuer servere gjør du følgende:

• Velg serverplassering i Server Locationseksjonen.
• Velg CentOS7under ISO Libraryfanen i Server Typeseksjonen.
• Velg maskinvarespesifikasjonene du trenger i Server Sizedelen.
• Klikk på Deploy Nowknappen.

Bruk View Consolealternativet for å få tilgang til VPS-forekomsten via noVNC-konsollen.

Trinn 2: Start CentOS 7 Text Mode Installer

Velg Install CentOS Linux 7alternativet.

Trykk på Tabtasten.

Gå inn textetter vmlinuz initrd=initrd.img inst.stage2=hd:LABEL=CentOS\x207\x20\86_64 quietslik at det ser slik ut vmlinuz initrd=initrd.img inst.stage2=hd:LABEL=CentOS\x207\x20\86_64 quiet textog trykk på Entertasten.

VPS vil nå starte opp i tekstmodus CentOS-installasjonsprogrammet. Du vil se en skjerm i noVNC-konsollen som vist på bildet nedenfor.

Trinn 3: Sett opp LVM på LUKS Full Disk Encryption

Bruk Alt + Right Arrow Keykombinasjonen for å navigere til TTY2-konsollen for å skrive kommandoer på kommandolinjen.

Skriv inn følgende kommandoer nedenfor for å lage en partisjon som inneholder GRUB2-oppstartslasteren, en ukryptert /bootpartisjon og en primærpartisjon som vil inneholde LUKS-partisjonen.

parted -a opt -s /dev/vda mklabel gpt
parted -s /dev/vda unit mb
parted -s /dev/vda mkpart primary 1 3
parted -s /dev/vda name 1 grub
parted -s /dev/vda set 1 bios_grub on
parted -s /dev/vda mkpart primary 3 259
parted -s /dev/vda name 2 boot
parted -s /dev/vda mkpart primary 259 100%
parted -s /dev/vda name 3 root

Skriv inn følgende kommando for å vise partisjonsoppsettet.

parted -s /dev/vda print

Deretter fyller du den navngitte rootfspartisjonen med pseudo-tilfeldige data. Dette vil ta litt over en halv time å fullføre.

dd if=/dev/urandom of=/dev/vda3 bs=1M status=progress

På CentOS 7 cryptsetupbruker kommandoene standard chiffer av aes-xts-plain64, standard nøkkelstørrelse på 256 biter og standard hash av SHA1. I stedet vil LUKS-partisjonen bli opprettet med det sikrere Serpent-chifferet, med en nøkkelstørrelse på 512 biter og med Whirlpool-hashen.

cryptsetup luksFormat /dev/vda3 -c serpent-xts-plain64 -h whirlpool -s 512

Skriv inn svarene når du blir bedt om det med følgende spørsmål, og trykk deretter på Entertasten:

• Er du sikker? (Skriv inn store bokstaver ja):YES
• Skriv inn passordfrase: strong-password
• Bekreft passordfrase: strong-password

Valgfritt: Sikkerhetskopier LUKS-partisjonsoverskriften

Advarsel Dette vil tillate root-pålogging og kopiering uten passordforespørsel. Drep denne SSH-serveren etter at du har hentet /tmp/luks-header-backup.imgfilen.

For sikker oppbevaring, lagre en kopi av LUKS-partisjonsoverskriften. Dette sikrer at hvis overskriften på LUKS-partisjonen din på en eller annen måte er skadet, kan den gjenopprettes. Hvis overskriften er skadet uten en fungerende sikkerhetskopi, går dataene dine tapt for alltid.

cryptsetup luksHeaderBackup /dev/vda3 --header-backup-file /tmp/luks-header-backup.img

For å kopiere /tmp/luks-header-backup.imgfilen fra serveren, må en SSH-server startes midlertidig ved å bruke den sikre kopien scppå en klientvert for å hente den.

Skriv inn følgende kommando nedenfor for å generere SSH-vertsnøklene.

sshd-keygen

Skriv inn følgende kommando nedenfor for å lage /etc/ssh/sshd_configfilen.

cp /etc/ssh/sshd_config.anaconda /etc/ssh/sshd_config

Skriv inn følgende kommando nedenfor for å redigere /etc/ssh/sshd_configfilen.

vi /etc/ssh/sshd_config

For å redigere filen, trykk på Inserttasten og bruk piltastene til å navigere til deler av filen som må redigeres.

På linje én endrer du tallet Port 22fra standardverdien til 22til et tilfeldig antall du velger mellom 1025og 65535. (Eksempel: port 25782)

Rull ned til linje nummer tretten, trykk på Endtasten og trykk på Entertasten.

På neste linje legger du til HostKey /etc/ssh/ssh_host_ed25519_keyog trykker på Entertasten.

På neste linje legger du til HostKey /etc/ssh/ssh_host_rsa_keyog trykker på Entertasten.

Trykk på Esctasten, skriv :wqog trykk på Entertasten for å lagre filen.

Standard nettverksgrensesnitt eth0trenger en IP-adresse. Skriv inn følgende kommando nedenfor for å tilordne IP-adressen som er oppført for din instans til eth0nettverksgrensesnittet.

dhclient

Skriv inn følgende kommando for å vise den tildelte IP-adressen. IP-adressen vil bli oppført umiddelbart etter inetog før netmask. (Eksempel: inet 192.0.2.1nettmaske)

ifconfig eth0

Skriv inn følgende kommando for å starte SSH-serveren.

/usr/sbin/sshd

Hvis du bruker scpkommandoen fra en kommandolinje på en klientmaskin, bruk følgende kommando nedenfor som en mal for å hente /tmp/luks-header-backup.imgfilen. Erstatt 25782med det faktiske portnummeret som er tildelt i /etc/ssh/sshd_config. Erstatt 192.0.2.1med den faktisk tildelte IP-adressen.

scp -P 25782 [email protected]:/tmp/luks-header-backup.img .

Etter henting av luks-header-backup.imgfilen, drep SSH-serveren umiddelbart ved å skrive kommandoen nedenfor i noVNC-konsollvinduet.

killall sshd

Åpne LUKS-partisjonen for å sette opp det fysiske LVM-volumet som skal ligge inne.

cryptsetup luksOpen /dev/vda3 centos

Input the passphrase created earlier to open the LUKS partition when prompted, then press the Enter key.

Enter passphrase for /dev/vda3: strong-password

Type the following command below:

ls /dev/mapper

It will contain the following files named centos, control, live-base and live-rw. The centos is the LUKS partition.

Type the following command below to create the LVM physical volume.

pvcreate /dev/mapper/centos

When successful, you will receive the following message:

Physical volume "/dev/mapper/centos" successfully created

Type the following command below to create the LVM volume group.

vgcreate ssd /dev/mapper/centos

When successful, you will receive the following message:

Volume group "ssd" successfully created

Type the following command below to create a LVM logical volume for a swap partition. Use sound judgment to create a swap partition, of the necessary size (-L = size of the volume), based on your VPS instance.

lvcreate -L 1G -n swap ssd

When successful, you will receive the following message:

Logical volume "swap" created

Type the following command below to create a LVM logical volume for the root partition. This will use the remaining free space while reserving five percent (5%) to contain LVM snapshots of your logical volumes if you so choose.

lvcreate -l 95%FREE -n root ssd

When successful, you will receive the following message:

Logical volume "root" created

Display the LVM physical volume.

pvdisplay

You will see text in the noVNC console similar to what is pictured in the image below.

Display the LVM volume group.

vgdisplay

You will see text in the noVNC console similar to what is pictured in the image below.

Display the LVM logical volume(s).

lvdisplay

You will see text in the noVNC console similar to what is pictured in the image below.

Type the following command below to deactivate the LVM volume group. This must be completed in order to allow cryptsetup to close the LUKS partition in the next step.

vgchange -a n

When successful, you will receive the following message:

0 logical volume(s) in volume group "ssd" now active

Close the LUKS volume.

cryptsetup luksClose centos

Type the following command below:

ls /dev/mapper

It will contain the following files named control, live-base and live-rw. The centos file, containing the LUKS partition, will be missing to ensure that that it was closed properly.

Type reboot and press the Enter key to reboot.

Step 4: Start The CentOS 7 GUI Mode Installer

Select the Install CentOS Linux 7 option and press the Enter key.

The VPS will now boot into the GUI mode CentOS installer. You will see a screen in the noVNC console like pictured in the image below. Select Install CentOS 7 (1) and press the Enter key.

On the WELCOME TO CENTOS 7 screen, click the blue Continue button (1).

Attention If you're not using the default language of English and the locale of the United States, input your language in the search bar (1). Click on the language (2) and the appropriate locale (3) associated with it. When satisfied, click the blue Continue button (4).

On the INSTALLATION SUMMARY screen, click on INSTALLATION DESTINATION (Automatic partitioning selected) (1) under SYSTEM.

On the INSTALLATION DESTINATION screen, select the I will configure partitioning (1) option under Other Storage Options (Partitioning) and click the blue Done button (2) at the top left of the screen.

On the MANUAL PARTITIONING screen, click on the Unknown expandable accordion (1). It will reveal three partitions named BIOS Boot (vda1), Unknown (vda2) and Encrypted (LUKS) (vda3).

With the BIOS Boot partition highlighted in blue (1), select the checkbox option of Reformat (2) next to the File System: accordion and click the Update Settings button (3).

Click on the Unknown partition (1) so that it is highlighted in blue. Select the checkbox option of Reformat (2) next to the File System: accordion. Select ext2 in the File System: accordion (3), enter /boot in the text field (4) under Mount Point:, enter boot in the text field (5) under Label: and click the Update Settings button (6).

Click on the Encrypted (LUKS) partition (1) so that it is highlighted in blue. Enter the passphrase you created for LUKS partition in Step 3: Setup LVM On LUKS Full Disk Encryption in the Passphrase: text field (2) and click the Unlock button (3).

A new Unknown expandable accordion (1) will appear. It will reveal two partitions named Unknown (ssd-root) and Unknown (ssd-swap).

With the Unknown (ssd-root) partition (1) highlighted in blue, select the checkbox option of Reformat (2) next to the File System: accordion. Select xfs in the File System: accordion (3), enter / in the text field (4) under Mount Point:, enter root in the text field (5) under Label: and click the Update Settings button (6).

Click on the Unknown (ssd-swap) (1) partition so that it is highlighted in blue. Select the checkbox option of Reformat (2) next to the File System: accordion. Select swap in the File System: accordion (3), enter swap in the text field (4) under Label: and click the Update Settings button (5).

Click the blue Done button (1) at the top left of the screen.

A box named SUMMARY OF CHANGES will pop up. Click the Accept Changes button (1). This will bring you back to the WELCOME TO CENTOS 7 screen.

Click on NETWORK & HOST NAME (Not connected) (1) under SYSTEM.

On the NETWORK & HOST NAME screen, move the slider (1), next to the right of Ethernet(eth0) field, from the OFF position to the ON position. If you want to use a custom hostname instead of the default (192.0.2.1.vultr.com) in the Host name: text box (2), change it. Click the blue Done button (3) at the top left of the screen. This will bring you back to the WELCOME TO CENTOS 7 screen.

When you are satisfied with the options on the WELCOME TO CENTOS 7 screen, click the blue Begin Installation button (1).

On the CONFIGURATION screen, click on ROOT PASSWORD (Root password is not set) (1) under USER SETTINGS.

On the ROOT PASSWORD screen, enter a strong password in both the Root Password: (1) and Confirm: (2) text fields. Click the blue Done button (3) at the top left of the screen. This will bring you back to the CONFIGURATION screen.

On the CONFIGURATION screen, click on USER CREATION (No user will be created) (1) under USER SETTINGS.

On the CREATE USER screen, enter your full name in the Full name text field (1), an username in the User name text field (2), a strong password in both the Password (3) and Confirm password (4) text fields. Click on the Advanced... button (5).

A box named ADVANCED USER CONFIGURATION will pop up. In the Add user to the following groups: text field (1) under Group Membership, enter wheel and click the Save Changes button (2).

Click the blue Done button (1) at the top left of the screen.

The post-installation process will now commence. It will take a few minutes to complete. When it is finished, click on the blue Reboot button (1) to reboot your VPS instance.

Navigate back to the VULTR Server Management Screen. Click on the Settings link at the top. Click on Custom ISO on the menu on the left side. On the Custom ISO page, click on the Remove ISO button to unmount the ISO and reboot into your CentOS 7 VPS instance. Click the OK button when prompted and the VPS instance will reboot.

Navigate back to the View Console window to access the VPS instance via the noVNC console. Refresh the window if noVNC has disconnected.

You will be prompted to enter the passphrase (Example: Please enter passphrase for disk primary (luks-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)!:) you created for LUKS partition in Step 3: Setup LVM On LUKS Full Disk Encryption. Enter the passphrase and press the Enter key.

You will then be presented with the console login prompt. You can now close the noVNC console window.

Step 5: Update The System

Log in via SSH with a regular user and update the system as follows.

sudo yum install epel-release -y
sudo yum clean all && sudo yum update -y

Step 6: Install Dracut-Crypt-SSH

While still logged in as a regular user, type the following commands below to install dracut-crypt-ssh.

sudo yum install wget -y
sudo wget -O /etc/yum.repos.d/rbu-dracut-crypt-ssh-epel-7.repo https://copr.fedorainfracloud.org/coprs/rbu/dracut-crypt-ssh/repo/epel-7/rbu-dracut-crypt-ssh-epel-7.repo
sudo yum install dracut-crypt-ssh -y

Type the following command below to install the nano editor to ease editing of files.

sudo yum install nano -y

You will need to edit the default grub file located in /etc/default/grub.

sudo nano /etc/default/grub

Insert rd.neednet=1 ip=dhcp between GRUB_CMDLINE_LINUX="crashkernel=auto and rd.luks.uuid=luks-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

Save the file by entering the following keyboard combinations. Press the Ctrl + x keys, press the y key and press the Enter key.

Regenerate you GRUB configuration file by type the command below.

sudo grub2-mkconfig -o /etc/grub2.cfg 

Backup the original /etc/dracut.conf.d/crypt-ssh.conf by typing the following command below.

sudo mv /etc/dracut.conf.d/crypt-ssh.conf /etc/dracut.conf.d/crypt-ssh.conf.orig

Create a new /etc/dracut.conf.d/crypt-ssh.conf file by typing the following command below.

sudo nano /etc/dracut.conf.d/crypt-ssh.conf

Copy and paste the following text below into the nano editor.

dropbear_acl="/etc/dropbear/keys/authorized_keys"
dropbear_ecdsa_key="/etc/dropbear/keys/ssh_ecdsa_key"
dropbear_rsa_key="/etc/dropbear/keys/ssh_rsa_key"

Create the directory keys under /etc/dropbear/, with the necessary directory permissions, that will hold the authorized_keys, ssh_ecdsa_key and ssh_rsa_key files.

sudo mkdir /etc/dropbear/keys/; sudo chmod /etc/dropbear/keys/

Generate the ssh_ecdsa_key and ssh_rsa_key files with the ssh_keygen program by typing the following commands below. Press the Enter key twice, for each command, when prompted for passphrases.

sudo ssh-keygen -t ecdsa -f /etc/dropbear/keys/ssh_ecdsa_key
sudo ssh-keygen -t rsa -f /etc/dropbear/keys/ssh_rsa_key

Change the file permissions on ssh_ecdsa_key, ssh_ecdsa_key.pub, ssh_rsa_key and ssh_rsa_key.pub by typing the command below.

sudo chmod 400 /etc/dropbear/keys/*_key; sudo chmod 444 /etc/dropbear/keys/*.pub

Generate public keys using the How Do I Generate SSH Keys? tutorial, found at the beginning of the tutorial under Prerequisites, for your prospective client operating system.

Copy and paste all the text in the public key into the /etc/dropbear/keys/authorized_keys file using the nano program by typing the command below.

sudo nano /etc/dropbear/keys/authorized_keys

You must first build the initramfs and any subsequent update of the dracut-crypt-ssh configuration. Type the following command below for the initial build of the initramfs.

sudo dracut -f

Once that's complete, your CentOS 7 install is set up to listen for your SSH client to connect and allow you to unlock the LUKS partition using your passphrase. You may now reboot your CentOS 7 instance by typing the command below.

sudo reboot

På klientsystemene dine, se seksjoner 3.3. Unlocking the volumes interactivelyog 3.4. Unlocking using thelås commandopp Dracut-Crypt-SSH GitHub-siden for enten å tvinge frem en passordfrasemelding eller bruke unlockkommandoen til å åpne LUKS-partisjonen fra SSH-klienten din.