Installing Debian on QNAP TS-41x/TS-42x

QNAP TS-419P from the front

Overview

In a nutshell, the installation of Debian on your QNAP TS-41x/TS-42x works like this: you use the QNAP firmware to write a Debian installer image to flash. When you restart your device, Debian installer starts and allows you to login via SSH to perform the installation. Debian will be installed to disk and a Debian kernel will be put in flash that will start Debian from disk.

If you follow this procedure, Debian 10 (buster) will be installed to your SATA disk and the QNAP firmware on disk and in flash will be replaced with Debian. Debian does not install a web interface to configure your machine, although it's possible to install such software. If this is not what you want, please don't proceed with the installation.

Please note that Debian 10 was the last release to support these devices. Debian 11 (bullseye) is not supported. Furthermore, please note that there are no security updates for Debian 10 anymore!

Requirements and Preparation

In order to install Debian on a QNAP device, you need the following:

  • A QNAP TS-410, TS-410U, TS-412, TS-412U, TS-419P, TS-419P+, TS-419P II, TS-419U, TS-419U+, TS-420, TS-420U, TS-421 or TS-421U.
  • An internal SATA disk.
  • A network connection.
  • Another machine on which you have a telnet and an SSH client. Telnet is included in Linux and Windows. SSH is included in every Linux distribution as OpenSSH and there is PuTTY for Windows.

Note: if you have a QNAP device with 1 GB of RAM (i.e. TS-420U, TS-421 and TS-421U), you have to apply this workaround first.

Making a Backup

You have to make a backup of all the data stored on your QNAP before starting with the installation of Debian since Debian will format the whole disk during the installation. Also, Debian will replace the QNAP firmware in flash, so it's also recommended to make a copy of the flash (mtd) partitions. Debian will only modify two flash partitions but it's a good idea to keep a copy of all partitions as you may need them to use the recovery mode. More detailed instructions for making a backup of your flash partitions will be given later.

Starting the Installer

Start your QNAP device and login via SSH. Some time after you start your machine, you will hear a beep and a bit later you'll hear a longer beep. Wait for a few more seconds and then connect to the machine via SSH. The username is admin and the password is admin too.

Once you are logged in, you can save the content of your flash partitions to a USB stick. Connect a USB stick to your QNAP and wait for the system to mount it. In my case, it was mounted at /share/external/sdi1 but you can find the location with the following command:

mount | grep external
/dev/sdi1 on /share/external/sdi1 type vfat [...]

On systems that have never been initialized with the QNAP firmware, the VFAT module may not be available. If your USB stick does not get mounted, put it back in your PC and format it with the ext3 or ext4 filesystem.

Now go to this directory and make a backup of your flash partitions:

cd /share/external/sdi1
cat /dev/mtdblock0 > mtd0
cat /dev/mtdblock1 > mtd1
cat /dev/mtdblock2 > mtd2
cat /dev/mtdblock3 > mtd3
cat /dev/mtdblock4 > mtd4
cat /dev/mtdblock5 > mtd5
cd
umount /share/external/sdi1

Disconnect your USB stick from your QNAP, connect it to your PC and to add the mtdX files to your regular backup.

Now you can go ahead and download the installer.

Download and Flash the Installer

In order to download the Debian installer images, issue the following commands:

mkdir /tmp/debian
cd /tmp/debian
busybox wget http://archive.debian.org/debian/dists/buster/main/installer-armel/current/images/kirkwood/network-console/qnap/ts-41x/initrd
busybox wget http://archive.debian.org/debian/dists/buster/main/installer-armel/current/images/kirkwood/network-console/qnap/ts-41x/kernel-6281
busybox wget http://archive.debian.org/debian/dists/buster/main/installer-armel/current/images/kirkwood/network-console/qnap/ts-41x/kernel-6282
busybox wget http://archive.debian.org/debian/dists/buster/main/installer-armel/current/images/kirkwood/network-console/qnap/ts-41x/flash-debian
busybox wget http://archive.debian.org/debian/dists/buster/main/installer-armel/current/images/kirkwood/network-console/qnap/ts-41x/model

These commands will download the Debian kernel, the installer ramdisk, a file with information about the support QNAP model, and a script to write the kernel and ramdisk to flash. You can now run the script by executing the following command:

sh flash-debian

Please note that this command will take about three minutes to run. You will see the following on your screen:

Updating MAC address...
Your MAC address is 00:08:9B:xx:xx:xx
Writing debian-installer to flash... done.
Please reboot your QNAP device.

Once the command has completed, you can reboot your QNAP device:

reboot
exit

The Installation

After you have flashed the Debian installer image and restarted your QNAP device, the Debian installer will start. Since the TS-41x/TS-42x does not have any IO device, SSH will be used for the installation. The installer will bring up the network, start the OpenSSH server and you can then connect to the device using SSH. You have to wait a few minutes after starting the system before you can connect. When the installer is ready, the status LED will change to solid green and your device will beep briefly to indicate that you can now login via SSH.

Please note that Ethernet port numeration differs between the QNAP firmware and Debian. Under Debian, eth0 is the port marked with "LAN2". On the TS-419P, this is the lower (and not the upper) connector! This means you have to swap the cable when you start the installer.

Since most TS-41x/TS-42x devices do not have an LCD, the installer cannot tell you which IP address to connect to or which password to use. (On the devices that have an LCD, the installer currently won't display the IP address either, sorry.) With regards to the IP address, the following strategy is used:
  • If your QNAP firmware is configured to use DHCP (the default configuration from QNAP), Debian installer will try to acquire an IP address with DHCP. If you have not initialized your QNAP firmware with QFinder, DHCP will be used. You can use the MAC address of your QNAP device to tell your DHCP server to give out a specific IP address to your machine.
  • If you configured a static address in your QNAP firmware, this configuration will be used. However, if your network configuration was incomplete (e.g. IP address or DNS were missing), the installer will use DHCP instead.
  • If DHCP is used but your DHCP server does not respond, the device will use the fallback address 192.168.1.100. If you are unsure what the address of your QNAP is, unplug the Ethernet cable, start the machine again, wait until Debian installer is ready for SSH and then plug the cable back in and connect to this fallback address.
Please make sure that the QNAP is on a local network to which only you have access since the installer uses a very generic password, namely install. The user is installer. Before you can connect to the installer via SSH, you have to remove the SSH key from the QNAP firmware from your known_hosts file: 
ssh-keygen -f ~/.ssh/known_hosts -R 192.168.1.100

Now connect to the installer (again, replace the address in the example with the actual IP address of your QNAP) and login as user installer with the password install:

ssh installer@192.168.1.100

When the installer starts, it will ask you to choose a mirror of the Debian archive. Since Debian 10 (buster) is no longer distributed on Debian mirrors, you have to tell the installer to install from archive.debian.org. First of all, scroll up in the list of countries until you find the first option, which allows you to enter information manually:

Debian installer: enter mirror manually

Enter archive.debian.org as the mirror hostname:

Debian installer: enter mirror hostname

And accept /debian/ as the mirror directory:

Debian installer: enter mirror directory

The installation itself should be pretty standard and you can follow the installation guide. The installer knows about the TS-41x/TS-42x and at the end of the installation it will flash a kernel and ramdisk that will automatically boot into Debian. It will also install the qcontrol package that can be used to control the fan, LEDs and beeper on your QNAP device.

Since the TS-41x/TS-42x boots from flash you don't have many limitations as to how you partition your hard drive. You can use LVM and RAID and a number of filesystems.

At the end of the installation, the installer will write the new kernel to flash. Afterwards you will get a confirmation that the installation is complete. Confirm, wait for the installer to finish and once your SSH session terminates, wait a few minutes before you can connect to your newly installed system via SSH. Your QNAP device will beep when you can connect via SSH. You will be able to log in your newly created user. (Note that root logins as disabled by default.)

Success

You should now have a complete Debian system running on your QNAP. You can use apt and other tools to install additional software.

Please note that Debian 10 was the last release to support these devices. There are no more security updates for Debian 10; please read the upgrade page on how you can modify your system to allow an upgrade to Debian 11 (bullseye). While this is not officially supported, it's the best solution since Debian 10 no longer receives security updates.

Finally, make sure to read the tips and tricks about running Debian on the QNAP TS-41x/TS-42x.