Rules and Regulations for Using Ïã¸ÛÁùºÏ²ÊO Computers, Printing, Remote Login and File Copy
The Observatory has two computer-equipped classrooms and a number of PCs to control our telescopes and astronomical cameras.ÌýAll classroom PCs are dual-boot and run MS-Windows and Linux (Ubuntu). Their use is governed byÌýrules and regulations. Each classroom hasÌýprintersÌýfor student use. User data is held on a central server and backed up daily. Files can be recovered by the sytem administrator up to six months after deletion.
The Linux-based computing resources at Ïã¸ÛÁùºÏ²ÊO are accessible over the internet viaÌýremote login. If you have any issues regarding hardware or software please contactÌýThomas Schlichter, the Ïã¸ÛÁùºÏ²ÊO Computing and Instrumentation Officer.
Please note that misuse by a student may lead to a withdrawal of access.
- Printing
All Ïã¸ÛÁùºÏ²ÊO printers can be accessed from Windows and Linux via the usual print dialogues. Command line printing is available under Linux.
Library Printer:
The Library houses a Xerox AltaLink A3/A4 colour printer and copier, with UNIX print queue name uclo_liblaser for stapled A4 B/W prints. Please see the Ïã¸ÛÁùºÏ²ÊO system administrator if you need colour printing.3rd-Year Classroom Printers (South Wing):
The default printer is an A4 black and white laser printer with UNIX print queue name ulo_swlaser.Printing from the Command Line:
The print system recognises a large number of filetypes and will print them correctly without additional user specification. For example, to print a file named test.jpg from the command line to the laser printer in the library, type:lp -d uclo_liblaser test.jpg
This will do all the necessary conversions and send the file to the selected printer. If the destination printer is omitted, the file will print on the default printer.
- Remote Access to the Ïã¸ÛÁùºÏ²ÊO Linux Cluster
By default, remote access to all Ïã¸ÛÁùºÏ²ÊO accounts is disabled, for security reasons. However, any user with a Ïã¸ÛÁùºÏ²ÊO account can request authorization for remote access by sending an email giving their name and Ïã¸ÛÁùºÏ²ÊO username to the Ïã¸ÛÁùºÏ²ÊO system administrator. You will normally then be added to the list of remote users within a day or two (and will be sent an email confirmation when this has been done).
[Please note that Ïã¸ÛÁùºÏ²ÊO accounts are normally only available for students undertaking coursework at the Observatory; and that only the GNU/Linux system – not Windows accounts – can be accessed remotely.]
Remote Login:
From Linux/Unix
To login from a Linux machine, type in the following at the command line:
ssh -l "your_ulo_username" -C -X unity.ulo.ucl.ac.uk
(where, of course, you should substitute the appropriate value for "your_ulo_username"). You'll then be prompted for your Ïã¸ÛÁùºÏ²ÊO password.
From Apple Mac OS X
To run X-Window applications remotely on a Mac you need to install . To enable remote running of OpenGL applications like 'nightfall' issue the command below in a Mac terminal (put the two lines below on a single line, followed by ENTER):Ìý
defaults write org.macosforge.xquartz.X11 enable_iglx -bool true
For XQuartz 2.8.0 and later settings have changed and you should enter this command (again, all on a single line followed by ENTER):
defaults write org.xquartz.X11 enable_iglx -bool true
You can find more detailed and up-to-date information here: .
For logins from machines running OS X, use:
ssh -l "your_ulo_username" -C -Y unity.ulo.ucl.ac.uk
From Microsoft Windows
To login from an MS Windows machine you need to have a Secure Shell (SSH) Client (likeÌý) installed. Enable "X11 Forwarding" before connecting to allow the display of graphical output (select Connection → SSH → X11 and tick the checkbox) .
For graphical output you'll also need an X-Window serverÌýrunning on your machine like ; download and install the latest Public Domain Release (currently version 6.9.0.31, direct download link ).
When started, XMing runs in the background and does not open an application window. To check if it's running look for the X-icon in your icon tray.
Running programs remotely
If you plan to do data processing or other compute-intensive tasks please "hop" from UNITY to URANIA by running
ssh -X urania
This will avoid heavy loads on the Ïã¸ÛÁùºÏ²ÊO login host UNITY and keeps it responsive for all users. URANIA is configured the same way as the Ïã¸ÛÁùºÏ²ÊO desktops, but will not be switched off arbitrarily.
- Ìý
Remote File Copy:
is a graphical user interface for file transfer and can be downloaded and installed on Windows and Mac OS X. On Linux you can usually use the package manager to install it.Ìý
A command line alternative on computers running unix-like operating systems (such as Linux or OS X) is the command:
sftp unity.ulo.ucl.ac.uk
or
sftp "your_ulo_username"@unity.ulo.ucl.ac.uk
They use SFTP, the .
On MS Windows machines you could also install an SCP client likeÌý.
Troubleshooting:
Remote login to the Ïã¸ÛÁùºÏ²ÊO Linux cluster is via , and is accomplished by connecting to the only Ïã¸ÛÁùºÏ²ÊO machine accessible from the outside:
unity.ulo.ucl.ac.uk (128.40.167.12)
ÌýThe host key fingerprints for UNITY are:
To enable access, youÌýmightÌýneed to edit your ssh "known hosts" file, if you get error messages and can't log in.SHA256: ECDSA: 533TsvOzbC7Lve9jjDOpReinbQx6p9PIKi+CQEx4lgY root@unity ED25519:ajoYFoDhqKCNu0G8K4polcM9CIbqpxH54v6jOusYQug root@unity RSA: QnhERucbznqWLdAGyS86ieNgvhe0a8yVz7IfSzDx9mM root@unity MD5: ECDSA: 9d:62:c6:7c:d7:95:7e:34:3b:65:27:d6:9a:9f:d2:ac root@unity ED25519:d7:1b:c1:e9:5a:34:63:f9:52:7b:91:09:a5:3b:dc:0b root@unity RSA: 3d:26:3e:bb:20:67:db:5a:17:02:e0:46:9c:7d:81:56 root@unity
If your ssh program reports a key mismatch in the "known hosts" file it will also show the file name and the line number of the key entry. Delete this line from the file, start a new ssh connection and wait for ssh to report an unauthenticated host:
The authenticity of host 'unity (128.40.167.12)' can't be established. RSA key fingerprint is 3d:26:3e:bb:20:67:db:5a:17:02:e0:46:9c:7d:81:56. Are you sure you want to continue connecting (yes/no)?
If the fingerprint matches one of the two forÌýUNITYÌýlisted above, you can answer withÌýyesÌýand the new host key will be added to your "known hosts"-file.
Usually you only get this message the first time you connect to a new host or after a key change. If this happens at any other time there might be an attempt of a "Man-in-the-Middle" attack and you should contact theÌýÏã¸ÛÁùºÏ²ÊO system administratorÌýfor advice before proceeding.
An explanation of how SSH works can be found atÌý .
Other problems:
If you encounter any other problems, run theÌýsshÌý(orÌýsftp) command again, but with theÌý-vvvÌýoption; this produces 'verbose' output which might give you an idea of what went wrong. If you still can't resolve the problem, email the output to theÌýÏã¸ÛÁùºÏ²ÊO system administratorÌýand he will try to help to resolve the problem.
Please include your name, username and the date and time when you tried to connect , the following in the email:
- ÌýYour name, username and the date and time when you tried to connect,
- the type of operating system of your machine (Linux, Apple Mac, Windows),
- the terminal output produced by ssh or the putty error message as text attachment (ideally) or screen shot.
Please do NOT send your password via email - this will result in your account being locked and a new password being issued - Ïã¸ÛÁùºÏ²Ê will NEVER ask you for your password.
Please note that remote-login problems can have a wide range of causes and might take some time to get resolved.
- Acessing data on the Ïã¸ÛÁùºÏ²ÊO Linux server from Ïã¸ÛÁùºÏ²ÊO Windows PCs
All telescope data is archived on the central Linux server. To access this data from Ïã¸ÛÁùºÏ²ÊO desktops running Windows connect to urania.ulo.ucl.ac.uk (128.40.167.10) via WinSCP or FileZilla.
- The Asteroid Cluster at Physics in Gower Street
The Asteroid cluster is operated by the Department of Physics and Astronomy and provides Linux-based computing facilities to the Department's undergraduate students. Access priority is given to MSci students working on final-year projects.
The cluster terminals are located in room A19 in the Physics Building.
The principal source of information is the department'sÌýAsteroids Cluster page.