Doing CSC 151 work remotely

There are four primary mechanisms for doing CSC 151 work remotely.

1. You can run a virtual machine on your laptop. A virtual machine is a simulated computer - it’s like you have a Linux workstation running within your Mac or Windows computer. This ends up being the most straightfoward approach. However, it does mean that you’ll need to spend a little work transferring files back and forth from MathLAN.

2. You can connect to the workstation using a protocol called ssh (for “secure shell”). This approach is relatively straightforward for Mac and Linux users, and more complicated for Windows users. Using ssh, all of your files are on the MathLAN, which is convenient. However, the ssh approach doesn’t always seem to work.

3. If you run Linux on your workstation, you can install the CSC 151 software on your computer. This requires some understanding of Linux system administration, and is not always reliable. (We do this with Debian and Ubuntu regularly.) Once again, you’ll have to deal with the files residing on your computer, rather than on MathLAN.

4. You can use an application called VNC to connect to the MathLAN. This approach seems to work well for people who want to work with the MathLAN software and have limited bandwidth. However, it requires a lot of extra work to do securely. It can pollute our workstations with running processes. And our instructions are currently not very good.

The remaining sections of this document describe various OS/mechanism combinations. They currently appear in no particular order. Note that none of the CS faculty use Microsoft Windows, so we are much less familiar with how well any of this works under Windows. Windows users should probably use the virtual machine.

Running a virtual machine on MacOS, Windows, or Linux

Follow the virtual machine instructions

Installing software on your Linux workstation

The instructions we use to set up the virtual machine are at https://github.com/GlimmerLabs/virtual-mediascheme/blob/master/Building.md You should probably do the parts labeled “More Things to Install” and “Install the Mediascript Tools”.

You should also learn how to transfer files between workstations. The rsync command, described in the virtual machine instructions will work well. (You can’t use the shortcuts given in those instructions.)

Using ssh from a Mac or Linux workstation

These steps should work on most modern Macintosh and Linux workstations. If you have a Mac, you will need to download XQuartz first.

The steps below refer to ssh.cs.grinnell.edu. Note that for the time being, you should connect to a computer in Science 3813, rather than ssh.cs.grinnell.edu. You might, for example, use asprey, avram, davies, easley, grinbergs, grothendieck, hermann, holberton, horwitz, jones, karpinski, keller, koenig, licklider, meltzer, papert, pnueli, rhodes, williamson or zakrajsek. (All of those should be suffixed with .cs.grinnell.edu)

1. Open a terminal window.

2. Type ssh -X USERNAME@ssh.cs.grinnell.edu. Make sure to fill in your MathLAN username.

3. When prompted, type your MathLAN password.

4. Type gimp &. Yes, you should include the ampersand.

5. Type drracket &. Yes, you should include the ampersand.

6. Wait a little bit.

7. Both DrRacket and GIMP should appear in new windows on your Mac.
   Proceed as normal. (Mac users will need to use the control key rather than the command key for DrRacket and GIMP.)

8. If DrRacket and GIMP don’t appear, record what message you get and ask your professor.

When you are finished, make sure to quit DrRacket and GIMP. Also, log out in the terminal window and then close the terminal window.

Using ssh from a Microsoft Windows workstation

About a decade ago, a student wrote instructions for connecting from Windows computers using PuTTY and Xming. Those are likely to still work correctly. If someone wants to write a simpler version of those instructions, we’ll put them here.

Using VNC securely on Mac, Windows, or Linux

Follow the poorly written VNC instructions

Using VNC insecurely on Microsoft Windows

You will need to install PuTTY and VNC Viewer.

1. Using PuTTY, connect to one of the MathLAN machines mentioned above. (In the future, this should be ssh.cs.grinnell.edu. For now, it should be backus, cocke, dahl, dodgson, fraenkel, gray, hartree, huffman, jevons, kemeny, kilby, leibniz, newell, scheutz, shaw, shockley, whitehead, or zuse. (All of those should be suffixed with .cs.grinnell.edu). You may be asked to confirm that you want to connect to that computer. You will be prompted to enter your MathLAN password.

2. In your PuTTY terminal window, type vncpasswd. It will prompt you for a new passowrd. This new password is only for VNC. Enter a password that others are unlikely to guess. (Only the first eight characters are significant.) Enter it again when prompted.

3. In your PuTTY terminal window, type vncserver. It should start a VNC server and give you a response something like the following

    New 'machine:2 (username)' desktop is machine:2
   
    Starting applications specified in /home/username/.vnc/xstartup
    Log file is /home/username/.vnc/machine:2.log
   

4. Make a note of the number after the colon. That’s called your “desktop”. In the example response, the desktop is 2.

5. Start VNC Viewer. It will prompt you for a machine. Type MACHINE.cs.grinnell.edu:590x, where MACHINE is the machine name you used with PuTTY and x is the desktop number. So, if I’d used dahl and had desktop 2, I’d write dahl.cs.grinnell.edu:5902. If the desktop number is greater than 10, don’t use the 0. If the desktop were 13, I’d write dahl.cs.grinnell.edu:5913.

6. A MathLAN-like window should appear with one terminal window.

7. Start GIMP by typing gimp &.

8. Start DrRacket by typing drracket &.

9. When you are done, quit GIMP, DrRacket, and VNC Viewer.

10. In terminal, type vncserver -kill :x, where x is your desktop number.