Internal SSH console

This is an old revision of the document!

All Unipi devices include a full-featured ARM-based Linux environment, which is accessible via a Secure Shell console after following the steps below. This allows the users of Unipi devices to fully leverage the incredible versatility provided by open-source software packages.

The process of enabling access to it differs slightly between the three generations of Unipi devices and is detailed below for Unipi Axon. The process for Unipi 1.1 and Unipi Neuron is the same as for ordinary Raspberry Pi.

Unipi Axon

Unipi Axon includes an internal SSH server which is disabled by default and must be enabled according to the instructions in the “Getting Started” leaflet packaged with the device. After the server is enabled it is possible to connect to the device via any SSH client in the local network. This guide is intended to help users who are not otherwise familiar with SSH and is not necessarily the only way of connecting to the device.

Necessary steps

The first step for connecting to the Unipi Axon SSH console is to enable remote access to the internal SSH server. The server is enabled via the Unipi Axon service interface; the interface can be accessed by following the steps below:

Hold down the small recessed button on top of the Axon device case using a thin-enough tool. The button can be found next to the USB port labels on the upper side of the device.
Power up the controller while holding the button down.
Wait until the device finishes booting into the Unipi service mode. This is indicated by the two rows of LEDs flashing in an alternating fashion.
Use a device with a web browser to connect to the Unipi Axon via Ethernet LAN or Wi-Fi. The process is slightly different between the two options:
1. Ethernet LAN: The interface will be accessible on IP address 192.168.200.200. The device will also attempt to acquire an additional dynamic IP address via DHCP if DHCP is available.
2. Wi-Fi: The Unipi Axon service mode will create a Wi-Fi access point with SSID “UNIPICONFIG” and password “unipi.technology”. The interface will be accessible on IP addresses 192.168.200.200 and 192.168.201.1

After accessing the web interface you should see a screen with multiple buttons. To enable the SSH server first press the button with “Enable ssh” in the centre of the screen and then the “Restart System” button in the upper right corner of the screen.

Setting up tools

There are many tools which can be used to connect to SSH servers. For this tutorial, we recommend using PuTTY. You can download the PuTTY installer from https://the.earth.li/~sgtatham/putty/0.70/w32/putty-0.70-installer.msi (a third-party link) or many other places on the web.

Connect via SSH using PuTTY

For using SSH you need to know the target controller's IP address. To detect the address you can follow this guide: Detecting the unit's IP address.

To connect to the controller we will use the PuTTY. You can use other SSH applications as well, but PuTTY is the most suitable for Windows OS. The program can be downloaded in the Useful tools.

You must enable SSH before connecting to the controller.

Upon finishing the configuration you need to disable the SSH access or change the user password!

Install the downloaded PuTTY following the installer's instructions. After that, launch the program through putty.exe (its default location is C:/Program Files/PuTTY).

After launch, the following window will appear:

Enter the IP address into the Host Name tab and check if the Connection type is set to the controller's SSH. Then click on Open. A security dialogue window will appear for the first time. Click on “Yes” to display the SSH terminal's command line.

A prompt to enter login and password will be displayed
The default login and password is:

Login: unipi
Password: unipi.technology

Login has a time limit. If the limit expires, login will be no longer possible and you need to restart PuTTY and log in again.

The password is entered as an invisible text, eg. if the cursor does not move when entering the password, it is not an error!

After a successful login to a Unipi PLC this screen will appear:

Securing the OS (SSH)

Securing the operating system is always needed to prevent unauthorized access to the Unipi units. Using a non-secured OS may lead to unauthorized tampering that can stop or limit the system's operation. In the worst-case scenario, it may also cause damage to the connected technologies or endanger personnel on the installation site.

For these reasons, it is important to properly secure the system each time a new project is created. Alternatively, you can disable the SSH access completely.

As the connection is provided by the SSH protocol, it is necessary to know the IP address or the mDNS address of the device and have an SSH client installed on your PC or tablet. Among the most frequently used clients for Windows OS is the PuTTY application - user guide and default passwords are available here.

Before continuing, make sure you are logged in as the right user (for example “unipi” on our OpenSource OS). You can verify this by whoami command.

unipi@S103-sn999:~$ whoami
unipi

Now letps proceed to change the password by entering the following command:

passwd

A prompt to enter and confirm the current and new password will be displayed. If everything is set correctly, the following message will appear:

Changing password for unipi.
Current password:
New password:
Retype new password:

The entire process is depicted below (the password is not visible during its entering):

unipi@S103-sn999:~$ passwd
Changing password for unipi.
Current password:
New password:
Retype new password:
passwd: password updated successfully

Was the password change unsuccessful?
If the password change fails, the following message will appear:

passwd: Authentication token manipulation error
passwd: password unchanged

To solve this issue, try to enter the command below and then repeat the password change process.

sudo mount -rw -o remount /

Next, it's good practice to sync the changes on the storage (eMMC or SD card). This can be achieved by the sync command:

unipi@S103-sn999:~$ sync

You can now logout from your SSH session, reboot the PLC or power it of and on and login back to verify that the password has been sucesfully changed.

If the password cannot be changed even after entering the command, please contact our technical support.