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Using SSH

What is SSH, and why do we use it?

The Computer Science department computers are only accessible remotely through Secure SHell (SSH), which provides similar functionality to telnet but through an encrypted session. In addition, SSH uses host keys to assist in verifying the authenticity of the host machine you are connecting to. SSH is a secure login method, similar to slogin, whereby a user's password is encrypted rather than sent as plain text. For more information, check out http://www.employees.org/~satch/ssh/faq/.

Currently, the CS department servers are all using OpenSSH

Accessing CS Department Systems

To access the CS department systems, you will need to use an SSH client. Although most Unix-based systems now feature SSH, Windows systems in particular do not come with SSH clients. If your web browser can run Java applets, you may use MindTerm. If you need to connect frequently, you may opt to use one of the standalone clients listed below by system.

Windows Clients

Freeware Clients

  • PuTTY is a free Win32 implementation of SSH, which as of Sep 6, 2000 is legal for download and use without restriction due to the public domain release of the cryptographic algorithm behind it. PuTTY is a very robust and complete SSH1/2 implementation and is highly recommended. PuTTY now supports X tunneling, making it a quick and easy way to use X windows on turing. The only downside is that ssh, scp, sftp, and the ssh keygen are all separate programs, which can be confusing or inconvenient.
  • SSH secure shell. From SSH.com, students can download this client with a non-commercial license for free. It implements scp, x windows tunneling, a gui, and ssh2 and it features many configuration options.
  • CHAFFEE . This does not implement a full terminal, just invdividuals command lines. However, it does implement scp, making it easy to transfer files back and forth from turing.
  • sshCE. An ssh client for Windows CE currently in Beta.
  • TTSSH is a an extension to the telnet client TeraTerm. Both are freely available (including source) and can be downloaded from the above link. It has been tested by staff. It doesn't have all the bells and whistles of some other implementations, and some of the default settings are annoying (most users will probably want to set Term size = Windows Size in the Terminal dialog box) but it works well and it is free.
  • Cygwin is an entire UNIX environment that is built to run on top of Windows. This is the tool of choice for many people who are doing serious work on Turing using a Windows system. Highly Recommended.

    Commercial Clients

    • F-Secure SSH. A client made by the people who invented SSH.
      1. You can download a 30 day trial version. Version 5.2 supports both SSH1 and SSH2 standards. The price is $115, with a 50% educational discount.

      2. F-secure is now on Kato! Look in //Kato/pc/apps/dept/cs/ssh/. The executable is tnt.exe. It is keyed so be sure to have keyaccess running. We only have a limited number of licenses on kato so if you run into problems of not being able to get a license please let the CS staff know (staffnow@cs.hmc.edu). We will add more licenses if the need arises.

        NOTE
        Some people have had problems running ssh from Kato. The symptom is that windows will complain that kalib32.dll does not exist. This is a dll needed by F-secure to run and most likely this file isn't in your windows directory. To fix the problem, go to //kato/pc/apps/windows and copy the file kalib32.dll to your windows directory (c:/windows on most machines). Now ssh should run fine.

      3. If you are a CS major or are taking a CS class then you can get an ssh license for your own machine. These licenses are available to computer science majors on a FIFO schedule. Joyce Greene, the computer science department secretary, will have five CD's containing the license software. You will be asked to sign out and to return the CD within 48 hours (except weekends). Your signature entry will indicate:

        • verification that you are a computer science major or currently taking a computer science course.
        • your room number and extension.
        • the number of personal licenses you will be using.
        • any other computer science student who will be using the CD during your check out period - their name, room number, etc.

        Note that these licenses are available only to computer science majors and to those taking computer science courses, e.g., CS 60. We do not have the resources to provide licenses to all students on the Harvey Mudd campus.

    • ZOC A full featured emulator offering support for virtually every communication standard known to modems. It has a 30 day evalution period and costs $69.

    Mac OS Clients

    Freeware Clients

    • MacSSH is a free ssh client provided under the GNU GPL for either PPC or 68k machines.
    • NiftyTelnet 1.1 SSH. An enhanced version of the original NiftyTelnet that adds support for the SSH protocall. Also supports scp.

    Commercial Clients

    • F-Secure SSH. A client made by the people who invented SSH. You can download a 30 day trial version. It may suffer from the same incompatabilities with ssh 1 as the Windows version. It is $99 with a 50% educational discount.
    • Darwin Is the UNIX core under OS 10.x , and comes with a build of OpenSSH.

    UNIX

    There are two commonly used versions of SSH on Unix. The original SSH (now a commercial program, but available for free for educational use) and OpenSSH, part of the OpenBSD project.

    Java

    • Mindterm is a freely available Java-based SSH client, available as both a Java application and a Java applet. In principle it should run under any Java 1.1 or 1.2 runtime environment. The terminal emulation isn't great but it is a usable option for those who don't have a better one.

    VMS

    • FISH is a free VMS SSH client that is no longer being maintained. Its replacement is BAMSE
    • SSH Server is actually an SSH sever for VMS which includes a crude client. It requires configuration and compilation so it is not for the timid VMS user.

    OS/2

    BeOS

    Using SSH on Turing and other CS machines

    ssh can be invoked in the either of the following ways from a Turing/etc. command line (both usages are equivalent): 

    $ ssh [-l remote_user_name] <remote_system_name>
$ ssh <remote_user_name>@<remote_system_name>
    In case you have trouble with opening up windows on the other machine (X-forwarding), try: 
    $ ssh -X <remote_user_name>@<remote_system_name>
    (Make sure the case is right, as -x disables X-forwarding)

    Copyright (c) HMC Computer Science Department. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with the no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License.''

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    • Last Modified Monday, 27-Jan-2003 14:55:10 PST