iSCSI | Earl C. Ruby III

I have an Ubuntu 24.04 “Noble Numbat” workstation already set up with LUKS full disk encryption, and I have a Terra Master F4-424 NAS with 32TB raw storage that I installed TrueNAS Scale on. Years ago I set up a LUKS-encrypted iSCSI volume on a Synology NAS and used that to back up my main Ubuntu server, and I wanted to do the same thing using TrueNAS.

Create the iSCSI volume on TrueNAS

Log into the TrueNAS Scale Web UI and select System > Services. Make sure that the iSCSI service is running and set to start automatically.

Select Datasets > Add Dataset to create a new storage pool.

Add Dataset
- Parent Path: [I used my main data pool]
- Name: ibackup
- Dataset Preset: Generic

Select Shares > Block (iSCSI) Shares Targets > Wizard to create a new iSCSI target.

Block Device
- Name: ibackup
- Extent Type: Device
- Device: Create New
- Pool/Dataset: [select the dataset that you created in the previous step]
- Size: 3 TiB [How many TiB do you want?]
- Sharing Platform: Modern OS
- Target: Create New
Portal
- Portal: Create New
- Discovery Authentication Method: CHAP
- Discovery Authentication Group: Create New
- User: CHAP user name (doesn’t need to be a real user, can be any name)
- Secret: CHAP user password (make sure you write the user name and password down)
- IP Address: Click Add. [If you only want one specific IP address to be able to connect, enter it. If you don’t care, use 0.0.0.0]
Initiator
- Initiators: [Leave blank to allow all or enter a list of initiator hostnames]
Click Save. You’ve now created an iSCSI volume that you can mount from across your network.

Get the iSCSI volume to appear as a block device on Linux

On your Ubuntu box switch over to a root prompt:

sudo su

Install the open-iscsi drivers. (Since I’m already running LUKS on my Ubuntu box I don’t need to install LUKS.)

apt-get install open-iscsi

Edit the conf file

vi /etc/iscsi/iscsid.conf

Edit these lines:

node.startup = automatic
node.session.auth.username = [CHAP user name on TrueNAS box]
node.session.auth.password = [CHAP password on TrueNAS box]

Restart the open-iscsi service:

systemctl restart open-iscsi
systemctl status open-iscsi

Start open-iscsi at boot time:

systemctl enable open-iscsi

Now find the name of the iSCSI target on the TrueNAS box:

iscsiadm -m discovery -t st -p $NAS_IP
iscsiadm -m node

The target name should look something like “iqn.2005-10.org.freenas.ctl:ibackup”

Still on the Ubuntu workstation, log into the iSCSI target:

iscsiadm -m node --targetname "$TARGET_NAME" --portal "$NAS_IP:3260" --login

Look for new devices:

fdisk -l | less

At this point fdisk should show you a new block device which is the iSCSI disk volume on the Synology box. In my case it was /dev/sda.

Set up the block device as an encrypted file system

Partition the device. I made one big /dev/sda1 partition, type 8e (Linux LVM):

gparted /dev/sda

Set up the partition as a LUKS-encrypted volume:

cryptsetup --verbose --verify-passphrase luksFormat /dev/sda1

You’ll be asked to type “YES” to confirm. Typing “y” or “Y” or “yes” will not work. You have to type “YES”.

Open the LUKS volume:

cryptsetup luksOpen /dev/sda1 backupiscsi

Create a physical volume from the LUKS volume:

pvcreate /dev/mapper/backupiscsi

Add that to a new volume group:

vgcreate ibackup /dev/mapper/backupiscsi

Create a logical volume within the volume group using all available space:

lvcreate -l +100%FREE -n backupvol /dev/ibackup

Put a file system on the logical volume:

mkfs.ext4 /dev/ibackup/backupvol

Add the logical volume to /etc/fstab to mount it on startup:

# TrueNAS iSCSI target
/dev/ibackup/backupvol /mnt/backup ext4 defaults,nofail,nobootwait 0 6

Get the UUID of the iSCSI drive:

ls -l /dev/disk/by-uuid | grep sda1

Add the UUID to /etc/crypttab to be automatically prompted for the decrypt passphrase when you boot up Ubuntu:

backupiscsi UUID=693568ca-9334-4c19-8b01-881f2247ae0d none luks

That’s pretty much it. The next time you boot you’ll be prompted for the decrypt passphrase before the drive will mount. If you type df -h you should see a new disk mounted on /mnt/backup.

If you found this interesting, you might want to check out my article Adding an external encrypted drive with LVM to Ubuntu Linux.

Hope you found this useful.

I have an Ubuntu 15.04 “Vivid” workstation already set up with LUKS full disk encryption, and I have a Synology DS414 NAS with 12TB raw storage on my home network. I wanted to add a disk volume on the Synology DS414 that I could mount on the Ubuntu server, but NFS doesn’t support “at rest” encrypted file systems, and using EncFS over NFS seemed like the wrong way to go about it, so I decided to try setting up an iSCSI volume and encrypting it with LUKS. Using this type of setup, all data is encrypted both “on the wire” and “at rest”.

Log into the Synology Admin Panel and select Main Menu > Storage Manager:

Add an iSCSI LUN
- Set Thin Provisioning = No
- Advanced LUN Features = No
- Make the volume as big as you need
Add an iSCSI Target
- Use CHAP authentication
- Write down the login name and password you choose

On your Ubuntu box switch over to a root prompt:

sudo /bin/bash

Install the open-iscsi drivers. (Since I’m already running LUKS on my Ubuntu box I don’t need to install LUKS.)

apt-get install open-iscsi

Edit the conf file

vi /etc/iscsi/iscsid.conf

Edit these lines:

node.startup = automatic
node.session.auth.username = [CHAP user name on Synology box]
node.session.auth.password = [CHAP password on Synology box]

Restart the open-iscsi service:

service open-iscsi restart
service open-iscsi status

Start open-iscsi at boot time:

systemctl enable open-iscsi

Now find the name of the iSCSI target on the Synology box:

iscsiadm -m discovery -t st -p $SYNOLOGY_IP
iscsiadm -m node

The target name should look something like “iqn.2000-01.com.synology:boxname.target-1.62332311”

Still on the Ubuntu workstation, log into the iSCSI target:

iscsiadm -m node --targetname "$TARGET_NAME" --portal "$SYNOLOGY_IP:3260" --login

Look for new devices:

fdisk -l

At this point fdisk should show you a new block device which is the iSCSI disk volume on the Synology box. In my case it was /dev/sdd.

Partition the device. I made one big /dev/sdd1 partition, type 8e (Linux LVM):

fdisk /dev/sdd

Set up the device as a LUKS-encrypted device:

cryptsetup --verbose --verify-passphrase luksFormat /dev/sdd1