How can I access Engineering Linux systems from home? : ENGR-IT Support

Accessing Linux Servers

In order to access a Linux system in the College of Engineering (CoE) you have several options and the work you need to do will determine the best option. If you just need log in and check a file, get some information, etc..., then using an ssh client will be a good choice. If you need to perform more work or need to run a graphical interface then X2Go is a good option. No matter how you decide to connect to the a server, you will need to be on the Engineering VPN. See How can I connect to the Engineering VPN for more information.

SSH Clients

An ssh client is the modern equivalent of a telnet client; it make a connection to a remote system, passes the credentials, and waits to see if the credentials were accepted. Once accepted, you are logged in and can issue commands. We have ssh clients available on the Software Licensing.

From the top, select the group you belong to;Students, Staff/Faculty... Navigate to the section you belong in, and then look on the right hand side of the middle section of the page of a heading "Security" and under that, select SSH. On this page you can select the SSH client you would like from the available choices. We have had good luck PuTTY and Tera Term...note WinSCP is for transferring files.

X2Go Client

NOTE: Compositing does not work correctly on XFCE with x2go

In order to delete the compositing feature, before you start your first x2go session, use ssh and login to one of our linux servers and at the command prompt enter:

xfconf-query -c xfwm4 -p /general/use_compositing -t bool -s false

now where was I ..... oh yeah,

Ssh is fine if you are do not need graphics since graphics will slow down the remote connection a little, so if you do not need graphics, then using an SSH client will work better (faster login/startup ). What if you need to use graphics. That is where X2Go comes in.

X2Go is an X windows server/client install that has been optimized for use over low bandwidth links. It is build on top of SSH protocols so it does not require extra firewall holes; it uses the SSH port. X2Go has built in compression and optimization code that allows a user to run any level of graphical application, from a single GUI window to a full desktop environment with a minimum impact on thee network.

To get your very own copy of X2Go, head over to the X2Go Website. At the Top of the page there s a section titled "Get X2Go". In that section, select the "Installing X2Go (client/server)". On the next page, select the "X2Go Client" link. From the clients page you will be able to select the client for your OS. If you run windows, then select the installer for MS Windows.

Once you download the installer it is time to install the application. When you are installing the client, select a "Custom" install. Then select all the fonts that the installer lists. Many of the engineering packages use older fonts which are not installed, by default.

Now we have X2Go installed, we need to define sessions. Start the X2Go client that we installed in the last step. You should see something similar to:

There are three sections: the menu bar, the connection area in the center of the page, and the list of sessions you have defined.

From the menu bar, click Session-> New. This will bring up a dialog box to set the parameters. You will then see this dialog:

To get started, pick a name for your session. In our example, we can see the session is named "Compute"; I usually name the session for the host I am connecting to or the host and the application. For example this image shows an XFCE session and is named for the host that it will connect to.

We strongly suggest that you create Single Appllication Sessions for work on compute.engr.arizona.edu. Compute.engr.arizona.edu is a highly shared asset and if everyone runs full desktop sessions, resources will be strained and the system performance will degrade. When you run a full desktop session you are running close to one hundred processes. Each taking resources from the system. If you create a single application session, the only process that you will run is that application.

If you want to create a session on compute that just runs Firefox, pick a name something like “compute-firefox” and specify the path to the executable.

Now we will go through each tab and set the values contained therein. The next tab is the “Connection” tab.

From this tab you tell X2Go what type of network you are on. If you are on campus and connected to the wired Ethernet, the select LAN; all the way to the right on the slider. If your connected to a different type of network, then select what is appropriate:

MODEM – slowest possible link
ISDN – really???
ADSL – This is what I use from my home to remote in
WAN – if you are across campus, but are not in a CoE building
LAN – you are on the same subnet as the server. This is what you will want to use if your are in a CoE building.

The Compression section is there if you are having throughput issues. I have never used this setting.

We will now move to the Input/Output tab.

This tab is where you set the characteristics of your display. The only setting that usually gets changed is the Display settings.

Then we move to the Media tab:

This section allows you to set up sound support and printing support. Set the sound support to your preference.

You do not want Client side printing support, unless you are running a Linux OS; client side printing requires SSHFS, which seems to be available on Linux only, for now.

Finally, you can setup shared folders. This allows you to drop a file into a “shared” folder on the client and the retrieve it from the server. While this could be very useful, I have not used it.