SSH and command line

What's SSH?

SSH stands for Secure Shell, and refers to a protocol that allows to remotely control and administer a machine using the command line interface (CLI). It is available by default in any terminal on GNU/Linux and macOS. On Windows, you may want to use MobaXterm (after launching it, click on Session then SSH).

The command line interface (CLI) is, in the computer world, the original (and more technical) way of interacting with a computer compared to graphical interface. Command line interfaces are generally said to be more complete, powerful or efficient than a graphical interface, though also more difficult to learn.

How to connect

Login credentials

  • If you are installing at home, the default credentials are login: root and password: yunohost (or 1234 if you flashed an armbian image)
  • If you are installing a remote server (VPS), your provider should have communicated you the login and password (or allowed you to configure an SSH key)

Address to use

If you are installing at home (e.g. on a Raspberry Pi or OLinuXino or old computer):

  • you should be able to connect to your server using yunohost.local.
  • if yunohost.local does not work, your need to find out the local IP of the server.
  • if you installed a server at home but are attempting to connect from outside your local network, make sure port 22 is correctly forwarded to your server.

If your server is a remote server (VPS), your provider should have communicated you the IP address of the machine

In any cases, if you already configured a domain name pointing to the appropriate IP, it's much better to use yourdomain.tld instead of the IP address.

Connecting

The SSH command typically looks like:

# before the postinstall:
ssh root@11.22.33.44

# or after the postinstall:
ssh admin@11.22.33.44

# avec le nom de domaine plutĂ´t que l'ip (plus pratique):
ssh admin@votre.domaine.tld

# using the domain name instead of the IP (more convenient)
ssh admin@yunohost.local

# if you changed the SSH port
ssh -p 2244 admin@votre.domaine.tld

N.B. : fail2ban will ban your IP for 10 minutes if you perform 10 failed login attempts. If you need to unban the IP, have a look at the page about Fail2Ban

Which other users may connect to the server?

By default, only the admin user can log in to YunoHost SSH server.

YunoHost's users created via the administration interface are managed by the LDAP directory. By default, they can't connect via SSH for security reasons. Via the permissions system it is possible to allow the connection in SFTP or if it is really necessary in SSH.

Be careful who you give SSH access to. This increases even more the attack surface available to a malicious user.

Go to Users > Manage groups and permissions.

From here, you can add SFTP or SSH permissions to any user or group.

If you want to add an SSH public key to the user, you have to do it from the command line, as the web interface does not yet offer this feature.

Security and SSH

A more extensive discussion about security & SSH can be found on the dedicated page.

The command line

Providing a full tutorial about the command line is quite beyond the scope of the YunoHost documentation : for this, consider reading a dedicated tutorial such as this one or this one. But be reassured that you don't need to be a CLI expert to start using it !

The yunohost command

The yunohost command can be used to administer your server and perform the various actions similarly to what you do on the webadmin. The command must be launched either from the root user or from the admin user by preceeding them with sudo. (ProTip™ : you can become root with the command sudo su as admin).

YunoHost commands usually have this kind of structure :

yunohost app install wordpress --label Webmail
          ^    ^        ^             ^
          |    |        |             |
    category  action  argument      options

Don't hesitate to browse and ask for more information about a given category or action using the the --help option. For instance, those commands :

yunohost --help
yunohost user --help
yunohost user create --help

will successively list all the categories available, then the actions available in the user category, then the usage of the action user create. You might notice that the YunoHost command tree is built with a structure similar to the YunoHost admin pages.

The yunopaste command

This command allow you to share with an other person the output of a command.

Example:

yunohost tools diagnosis | yunopaste

The ynh-vpnclient-loadcubefile.sh command

This command is only available if you have the VPN Client application installed. You can use it to load a new .cube in case you can't get to the VPN Client interface to do so.

ynh-vpnclient-loadcubefile.sh -u <username> -p <password> -c <path>.cube

Some useful commands

If your administration web interface indicates that the API is unreachable, try starting yunohost-api:

systemctl start yunohost-api

If you can no longer connect with the user admin via SSH and via the web interface, the slapd service may be down, try restarting it:

systemctl restart slapd

If you have manually modified configurations and want to know the changes:

yunohost tools regen-conf --with-diff --dry-run

Found errors? Think you can improve this documentation? Simply click the Edit link at the top of the page, and then the icon on Github to suggest changes.