Using SSH

Computing Services Information Document - Sun/Unix

SSH (Secure Shell) is a program for logging into a remote machine and for executing commands on a remote machine using encryption to secure the connection. It is intended to replace telnet, rlogin and rsh, by providing secure encrypted communications between two untrusted hosts over an insecure network. X11 (X-Windows) connections and arbitrary TCP/IP ports can also be forwarded over the secure channel.

Secure FTP - This SSH client also has an integrated secure ftp client. For more information on sftp, see our SFTP web page.

SSH makes its initial connection to another system running ssh, using the RSA public/private key setup. The system you are connecting to will exchange secure keys with the system that you are sitting at, in such a way, that both machines can verify each other and give the okay to login. Then every packet sent between the machines (including any passwords) is encrypted using one of several modern encryption methods (idea, des, etc..) This means the original connection is verified, and can't be host spoofed, packet sniffed, dns spoofed, etc.

NOTE TO CABLE MODEM USERS: Cable modem connections are frequent targets of hackers. They will run software that listens to the network traffic from your cable modem and "sniffs" out packets of data for them. From these "sniffed" packets a hacker may obtain your password or other personal information. The unsavory people who do this sort of thing will have a very hard time getting to that information if it is transmitted using encryption. Although encryption is not a 100% guarantee of security, it is many times better than using no encryption at all.

How to Use SSH:

We are working on documentation for the Macintosh version of SSH, but in the meantime, you can download a copy of MacSSH from www.macssh.com

Connecting to clamshell or crabshell from SSH.com's SSH for Windows:

If you are going to use the Windows version of the secure shell program (also referred to as a secure shell client) to connect to clamshell or crabshell, then all you need to do is install the client program.

The specific files needed are found at: http://software.rutgers.edu/

Login with a valid netid/password. Then pick "Search Software" and search for the keyword "ssh". Click on the link for Secure Shell.

Save the SSHWin executable file to your Desktop, or anywhere on your hard drive if you want to keep the file after you are done installing it. Once the file has finished downloading, double-click on the file icon (either on your desktop or on your hard drive, if that's where you saved the file) to install SSH for Windows. Follow the on-screen instructions. If you wish to use commercial secure shell for Windows beyond the 30 day trial period, you must go to their site, www.ssh.com and apply for an educational use license.

After you have installed the client software, click the "Secure Shell Client" icon in the SSH Secure Shell sub-menu of your Start Menu, and do the following:

Click on File, then click on Connect

In the dialog box that appears, type in the full hostname of the system you want to connect to.
For students - clamshell.rutgers.edu
For faculty/staff - crabshell.rutgers.edu

Then type in your username for that system, and click on the "Connect" button.

Yes

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Finally, type in your password for that system and click on OK.

Using Profiles:

If you consistently connect to more than just one remote host computer, you probably want to have different settings defined for each host. Profiles make it easy to manage different host configurations. Adding a new profile is extremely easy. When you have connected to a new host computer, the "Add Profile" dialog box will open:

Type in a name for your connection, and press the "Enter" button. When you later want to connect to the same host, just select its profile under the "Profiles" option.

To edit existing profiles, click on the "Profiles" menu in SSH, then choose "Edit Profiles":

You will have the opportunity to customize the settings for each of your profiles. To save the changes you've made, click on the "OK" button, otherwise, choose "Cancel".

Using "Quick Connect":

Select the Quick Connect option (from the toolbar or from the File menu) to establish a completely new SSH connection that can be operated independently of any other clients and connections. You can connect to an entirely new remote host computer and still keep the old connection to a different host open.

When you need to establish a new connection, just click the Quick Connect button to connect to a new host with the default settings.

Once connected, you can then customize the settings to match your exact requirements for this particular host and save the settings as this host's profile

Printing:

Select the Print option to output the contents of the current scrollback buffer to your printer. Use the "Print Preview" option to help you to determine which pages to print and how the printout will look like.

Logging a Session:

Choose the Log Session option to save an entire transcript of the current terminal session to a file.

When Log Session is selected, the "Save As" dialog opens, asking for a filename for the log file. This file will be created if it does not already exist, and it will contain a transcript of the connection. When logging is active, a checkmark appears next to the Log Session menu option. Selecting the Log Session menu item for a second time stops logging.(checkmark will dissappear)

File Transfer:

SSH allows the opportunity to open a "File Transfer Window" that can be used to upload information from your local computer to the remote host. Click on the "Window" menu, then click on "New File Transfer"

More information about SSH's file transfer feature (SFTP) can be found at:
http://www.camden.rutgers.edu/HELP/Documentation/Unix/S50-1325-sftp.php

For further details on using SSH, please review the application's help menu (Help --> Contents), or e-mail help@camden.rutgers.edu

Connecting from a Unix/Linux SSH client to clamshell or crabshell:

Run the ssh client:

To login to a remote system using ssh2 protocol, simply give the ssh command along with the name of the host, like this:

ssh clamshell.rutgers.edu

ssh will start an encrypted connection between the local computer and the remote host, if this is the first time that you have used ssh to login to the remote host, you will see a message warning you that the host's key is being added to your personal list of known hosts (stored in a ~/.ssh2/hostkeys). Because you are using the ssh2 protocol, the system will prompt for your password on the remote host before allowing you to login.

You can also use ssh as a replacement for rsh by sending remote commands. This is done in much the same way as using ssh to login to a remote hosts:

ssh <host name> <command name>

ssh clamshell.rutgers.edu who

Since ssh2 is backwards-compatible with ssh1, you can also use the command:

ssh1 <host name>

ssh1 <host name> <command name>

to either login to a remote host or execute a command on a remote host. The ssh1 program supports "no password" logins in conjunction with the .rhosts file in your home directory. It also uses an older version of the ssh protocol, so you really should not use ssh1 unless the remote system does not support ssh2. Clamshell and crabshell both support ssh2.

Please note that we only provide ssh1 support for outgoing connections. The ssh1 protocol is old and riddled with security holes, so as of November 2001 Camden Computing Services no longer supports incoming ssh1 connections.

For additional help with ssh see "man ssh".

Questions/comments regarding Camden Computing Services or this web site
can be directed to: help@camden.rutgers.edu.
Last updated: July 21, 2010, 10:39 EDT.
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