Shell access via SSH

You can use SSH to access a shell from your PC. This is useful for debugging or more advanced shell usage.

You need a SSH key-pair for this. Logging in via password is disabled by default.

Create your public key

If not already created, create your public key. Default choices should be fine for LAN. You can leave empty password if you don’t want to deal with it each time:

ssh-keygen

Copy the public key to your device

You need then to transfer your public key to your device. There are multiple ways to do this. These are a few options:

  • Connect the UBports device and the PC with a USB cable. Then copy the file using your file-manager.

  • Or, transfer the key via the Internet by e-mailing it to yourself, or uploading it to your own cloud storage, web-server, etc.

  • You can also connect via adb and use the following command to copy it (Some devices cant support ADB, check the devices page to learn more.):

    adb push ~/.ssh/id_rsa.pub /home/phablet/

Configure your device

Now you have the public key on the UBports device. Let’s assume it’s stored as /home/phablet/id_rsa.pub. Use the terminal app or an ADB connection to perform the following steps on your device.

mkdir /home/phablet/.ssh chmod 700 /home/phablet/.ssh cat /home/phablet/id_rsa.pub >> /home/phablet/.ssh/authorized_keys chmod 600 /home/phablet/.ssh/authorized_keys chown -R phablet:phablet /home/phablet/.ssh

Now start the SSH server:

sudo systemctl start ssh.socket

Connect

Now everything is set up and you can use ssh

ssh phablet@ubuntu-phablet

or, if that does not work

ssh phablet@<ip-address>

To identify the IP-address of your UBports device, open the Terminal app on your device and run the following command:

hostname -I

The output is a list of IP addresses separated by spaces. Use the IP address that matches your subnet. On your PC or laptop:

debian2:~/$ hostname -I 192.168.42.41 2001:982:89e9:1:bc6b:758:7ba2:c190

On the phone:

phablet@ubuntu-phablet:~$ hostname -I 10.55.74.177 192.168.42.52 2001:982:89e9:1:ef68:5f7c:3db4:c0d3

In this case you use the second IP address

Of course you can now also use scp or sshfs to transfer files.

Configuration

you can enable ssh on boot by running the following command:

sudo systemctl enable ssh.socket

you can edit the port ssh is listening on with the following command:

sudo systemctl edit ssh.socket

then add the following text:

[Socket] ListenStream= ListenStream=[customPort]

Troubleshooting

If connecting fails with the message

kex_exchange_identification: read: Connection reset by peer

check the log on the UBports device

journalctl | grep sshd

If you see a message about missing hostkeys such as

sshd: no hostkeys available -- exiting.

You need to generate host keys with the following command

sudo ssh-keygen -A

References