Remote Access Using Linux/Unix

OpenSSH is an SSH v1.x and v2.x compliant SSH package that is available for many Linux and Unix operating systems and is " ...freely usable and re-usable by everyone under a BSD license... ". OpenSSH also includes secure copy (scp), which may be used instead of ftp. It is available from:

ftp://ftp.openssh.com/pub/OpenBSD/OpenSSH/portable/.

Remote Logins

If you are using a UNIX based system (IRIX, Linux, SunOS, etc) you will typically need to type the following command from a shell terminal:

ssh yourusername@eos.tamu.edu

where yourusername is your account username for the system, eos.tamu.edu in this example. You will then be prompted for your Hydra cluster account password in order to establish the connection.

If, however, you are connecting for the very first time, you will see a message similar to the following, before arriving at the password prompt:

The authenticity of host 'eos (165.91.16.22)' can't be established.
RSA key fingerprint is f0:3e:2d:95:1b:56:b8:cb:6c:a5:92:1b:cd:1b:bf:92.
Are you sure you want to continue connecting (yes/no)?

Type yes and you will then be presented with the password prompt.

Warning: Permanently added 'eos.tamu.edu,165.91.16.22'
(RSA) to the list of known hosts.
yourusername@eos.tamu.edu's password:

File Transfers

Use SCP to copy files from one machine to another. SCP replaces rcp and should be used instead of ftp. It also has more flexibility than ftp and can be used to copy directories instead of just files. The general form of SCP is:

scp [[user@]host1:]filename1 [[user@]host2:]filename2 

Where filename1 and filename2 can be file or directory names. If your user name is the same on both the local and remote machines, then you do not have to provide the user@. If you are copying from your local machine, you do not have to provide the name of host1. For example, to copy a file called temp.ps from a local machine to eos.tamu.edu, use the following command:

scp temp.ps eos.tamu.edu:temp.ps 

The file temp.ps will be copied to your home directory on Hydra cluster. If you have a different user name on Hydra cluster, then specify it as shown below.

scp temp.ps remote-user-name@eos.tamu.edu:temp.ps 

Remote Display of Programs with Graphical Interfaces

Typically, if you use a graphical login screen to login a Linux or Unix system, then the system is already running a X11 server. You will need to login with SSH to the remote system in a slightly different manner:

ssh -X yourusername@eos.tamu.edu

The -X option tells SSH to allow programs to forward and display their graphical interfaces. This is known as X11 forwarding. To verify that X11 forwarding is working, type the following command:

xterm

If a new xterm terminal window for the remote system pops up, then X11 forwarding is working correctly.