UNIX Primer

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Connecting Remotely

It is often useful to connect to eniac-l from home. In order to do this, you can use the following:

Macintoshscp (see commands list below)
ssh (see commands list below)
WindowsFileZilla (see supported products)
SecureCRT (see above link)

To connect to another server from the UNIX computer you are currently working on (eg. from a lab computer to eniac-l.seas.upenn.edu) we use the 'ssh' (secure shell) command described below. To close a connection, you can 'logout' or 'exit' the topmost shell.

However, sometimes connecting through ssh does not allow us to use GUI programs. This is because 'X-forwarding' is not enabled. X-forwarding is what allows X-Windows (UNIX GUI) programs to run over a remote connection. If you find that this is the case, you can re-connect using 'ssh2' and the '+x' option, which forces X-forwarding.

To connect to a school computer from home, we recommend that you use one of the supported programs located on the PennConnect CD and available from Penn Computing Supported Products link. These programs are SecureCRT for PC users and Putty for Mac users, which are both provided free of charge to Penn students. These programs will allow you to log on to servers such as eniac-l from home.

When logged on from home through the ssh protocol (through SecureCRT or Putty) you will not be able to use programs that have a GUI. These types of programs cannot be run remotely unless you have a program that supports X-forwarding. These programs are generally extremely expensive. You can find the names of a couple of these programs in the 'See Also' section of this page.

Related Commands:

NameMeaningPurpose
ssh Secure SHell To connect remotely to another server as if you were logged on to that server.
Syntax
ssh <hostname>
ssh <username>@<hostname>
Notes
  • This program assumes that you are using the same username on the target server as you use on your current server. To override this, use the second provided syntax.

NameMeaningPurpose
ssh2 Secure SHell 2 To connect remotely to another server as if you were logged on to that server.
Syntax
ssh2 <hostname>
ssh2 +x <hostname>
ssh2 <username>@<hostname>
Notes
  • To enforce X-forwarding, use the second syntax (the +x option).
  • This program assumes that you are using the same username on the target server as you use on your current server. To override this, use the third provided syntax.

NameMeaningPurpose
scp Secure CoPy To securely copy a file on a remote server to the server you are currently using. For instance, you might use this to copy something from the '/tmp' directory on eniac-l to the '/tmp' directory on a lab computer you are using.
Syntax
scp <username>@<hostname>:<source_filename> <dest_filename>
Notes
  • You will be prompted for a password before file transfer takes place.

See Also:


Designed by D. Kaminsky
Edited by Diana Palsetia
© University of Pennsylvania, 2008