Remote access to a Linux host's desktop with VNC

The following article explains how to access the desktop of a Linux host residing inside the ETH network from another host on the in- or outside by using Virtual Network Computing (VNC)¹. Throughout his article, the following placeholders are used:

• current_host: This is a remote host in- or outside the ETH network, i.e. your office computer or home computer; the host you are currently working on. It will run the software to view a remote Linux desktop, the VNC viewer.

• gateway_host: This is the entrance gateway to the ETH network to bypass the firewall restrictions for connections from the outside, by the name of login.ee.ethz.ch. It is used to tunnel SSH connections in case you choose not to use VPN.

• internal_host: This is the target host you intend to connect to. If it's your personal PC in your office you know its name. Students can use an arbitrary shared student room PC like tardis-d12. If you're using a shared student PC, check it's availability at login.

• eth_username: This is the username you use to log in anywhere on an ETH provided IT service.

• eth_password: This is your password used in combination with your eth_username which lets you access ETH provided IT services, except for network authentications (see below).

• eth_network_password: This is your password also used in combination with your eth_username which is used for authentication to network services like Wifi and VPN. It is different from your eth_password.

Connect to the ETH network

If current_host resides outside of the ETH network, you need to connect to it by initiating a VPN connection. The following steps explain the necessary prerequisites.
If current_host is alreay inside the ETH network, skip to the next paragraph.

Know your eth_network_password

If you're unsure about your eth_network_password, login on password.ethz.ch with your regular eth_password and change your former eth_network_password to a new password.

Install the VPN client on current_host

• Go to sslvpn.ethz.ch and follow the instructions provided there to download, install and configure the Cisco AnyConnect VPN client provided by central IT services.

• To log in here you have to use your eth_username in combination with your eth_network_password.

• If you have access to additional realms, a.k.a virtual private Zones (VPZ), you can list them by visiting realms.ethz.ch.

Initiate a VPN connection

• Now you are ready to connect the VPN client on current_host to the ETH network and continue with the following steps.

Start a VNC server on internal_host

To start a VNC server instance on internal_host, you need to initiate a SSH connection to it.

Initiate a SSH connection to internal_host

• If current_host is a Linux client, issue the command ssh eth_username@internal_host in your terminal and log in with your eth_password.

• If current_host is a Windows 10 client you can use the optional installable feature (Apps -> Optional features -> OpenSSH Client) to issue the command as described for a Linux client above.

• Alternatively, you can follow the article about WindowsDirectSSHAccess for a comfortable setup with putty on Windows.

Setup and start the VNC server

View and control your remote Desktop on host C

VNC viewer software

The listed VNC software contains a viewer component and is available for both Linux and Windows:

• TightVNC: Opensource

• TigerVNC: Opensource, a fork of TightVNC with additional features

• TurboVNC: Opensource, a fork of TightVNC with peak 3D/video performance as a goal

• RealVNC: Freeware

The above list is not meant to be complete, feel free to install other solutions on your own on your home computer.

• TigerVNC viewer is installed on managed Linux clients
• On managed Windows clients, RealVNC viewer is installed on request

Check (student) host availability

Check with the command htop if any other users are using C's resources right now. If they do, log out and log in to a different host.
A list of student hosts can be shown by issuing the command grep tardis /etc/hosts

And Mac users?

To be documented. Hint: Everything you need is already available in macOS.