Remote Access to the CS Linux Machines

Overview

This page briefly describes how to access the CS department's Linux machines ``remotely'' -- i.e., how to use them if you are not sitting in front of them. For more details, or if anything described here does not work, talk to your instructor or send e-mail to the CSAdmin address posted in the labs.

What machines are available

The department maintains a number of computers that are accessible to anyone with an account on our system(s); every student who is taking or has taken a course in either the CSCI or ENGR departments should have such an account. Such machines include:

Remote access from another UNIX/Linux system

At one time in the dim past, users were able to remotely log into one of the department's Linux machines using one of the standard UNIX remote-login commands, telnet and rlogin. For security reasons, we now disallow this; you must use the newer and more secure command ssh.

To connect to remoteMachine as user userName, use the command ssh userName@remoteMachine. userName here is your username, and remoteMachine is the name of the computer you want to access. (You may need the full name of the machine, including the suffix cs.trinity.edu.) For more information, read the man page for ssh. Normally ssh will prompt you for a password; you can find instructions for setting up access using keys instead in my notes on passwordless login.

Once you have logged in, you can execute any text-based program (ls, vi, etc.). Depending on how your local machine is set up, you may also be able to run programs with a graphical component (firefox, gvim, etc.). If you have trouble, first try re-executing the ssh command with the flag -Y (e.g., ssh -Y userName@remoteMachine), and then ask for help if that does not work.

To transfer files, you can use the command ftp or the newer and more secure command sftp. If you only need to transfer a single file, or a set of files easily referenced by a regular expression, scp may be more convenient and is just as secure. For example, the command scp remoteMachine:/full/*.txt . transfers a group of files matching the wildcard. For any of these commands, read the man page(s) for details.

Remote access from a Windows system

At one time in the past, users were able to remotely log into one of the department's Linux machines using the standard Windows telnet program. For security reasons, we now disallow this; you must now use a program that supports the newer and more secure SSH connection protocol.

Probably the best (most complete) solution is Cygwin, which provides a UNIX-like environment under Windows. It should be installed on all the CS Windows machines; when you click on its icon, you should get something that looks like a Linux terminal window, and you can execute the commands described above for accessing one UNIX/Linux computer from another. Cygwin is free and available for download at http://www.cygwin.com.

If all you need is a terminal emulator (something that behaves like a terminal window and lets you execute text-only programs such as gcc and vi), we like the free program PuTTY. It should be installed on all of the CS department's Windows machines, and may be installed on other campus machines as well. It is also available for download at http://www.chiark.greenend.org.uk/~sgtatham/putty.html. It does not support programs with a graphical component (firefox, gvim, etc.); for that we recommend Cygwin, though there are other solutions (do a Web search for ``X server'' and ``Windows''). To use PuTTY, start it up, make sure the SSH radio button is selected, type the name of the machine you want to access into the ``Host name or IP address'' box, and click ``Open''. (You may need the full name, i.e., including the cs.trinity.edu suffix). You should then get a terminal window prompting you for your (Linux) username and password.

To transfer files, you should be able to access your Sol home directory from your Windows account by clicking ``Run'' and then typing \\sol.cs.trinity.edu. (``Should'' here is significant -- our intent is for it to work from inside the Trinity domain, but whether it does seems to depend on how Windows is set up. Ask if you try it and it doesn't work.)

Remote access from a Macintosh system

For Mac OS X, starting the Terminal application gives you something very like a Linux terminal window, in which you can use most or all of the commands described previously for accessing one UNIX/Linux system from another. The possible exception is connecting in a mode that supports running graphical programs; if the instructions above do not work, you may need to install additional packages; talk to your instructor or one of the admins.

Remote access from off-campus

All of the above assumes that you are trying to log in from a computer inside the Trinity domain. There are two mechanisms for getting access from off-campus:



Berna Massingill
2015-10-23