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    math.umn.edu / systems_guide / ssh

Secure Shell (SSH) for Remote Access and File Transfer

Ssh is used for encrypted point to point terminals and data copying across the internet. Ssh can be used for getting command line terminals to remote computers (similar to telnet) or to securely copy data using the scp command. Ssh is more secure than it's telnet and ftp predecessors.

If the unix command line is new to you, pick up a book on Unix from a local library.

If ssh, scp and rsync are new to you, check their manual pages by running a command like man ssh. For technical details, see RFC 4251: The Secure Shell (SSH) Protocol Architecture (and RFCs 4250, 4252-4254).

Other remote access guides around the U of M...

Remote Shells with SSH

To get a terminal shell on the remote computer shell.example.edu with a username johndoe, you can open a terminal on your local computer and run the command: "ssh johndoe@shell.example.edu". Then you'll be prompted to enter your password. Replace shell.example.edu with a hostname from the labs.

SSH terminals in different OSes - Linux has terminals available in the top-left corner in the "Applications > System Tools" menu. Mac OS X keeps the Terminal application in the folder "/Applications/Utilities/". Windows users generally use a program like PuTTY or Cygwin. SSH apps are available for portable devices like iOS and Android.

Remote Graphical Environment with FastX

To get the complete graphical environment on a remote linux machine see the FastX guide.

File Transfer with SFTP

Command Line SFTP

Remote files are specified with a username, a host and a file (or directory): user@hostname:file

Take a look at sftp and rsync after getting familiar with scp.

Drag and Drop SFTP

Desktop programs are available that let you drag and drop files between remote hosts and your desktop. Often they'll have you specify the user, host and password on an initial config screen. After connecting the SFTP sofware will show two panels, one panel. Then you can drag and drop between the panels and your desktop, file manager, or finder window.

See the web site for the software you plan to use.

Sftp Connection as a Mounted Drive

Software is available to mount the sftp connection as a network drive. The advantage over a command line program, or a a drag and drop sftp client is that with sftp mounted as a drive, desktop apps can use remote files directly.

SSH Software

Various free (or free for noncommercial use) ssh clients are available for different operating systems:

Unix

Command line clients like OpenSSH, DropBear SSH or Lsh generally behave the same with the ssh jdoe@shell.example.edu command. The OpenSSH page also has pointers to clients for various other platforms, and may be more current than this page.

Graphical and text user interfaces are available for ssh with the gftp and midnight commander software.

Many Linux desktops use Gnome for their desktop software, and can make sftp connections with the Nautilus file manager. Just find the "Location:" bar and put the sftp URL in it (something like sftp://jdoe@foobar.example.edu/home/jdoe). For a more permanent connection, go to the menu File > Connect to Server..., select the service type SSH and fill in fields with values like the previous URL.

One drawback of Nautilus network mounts is currently they aren't available from the command line shells. To have ssh/sftp mounts available in the command line you would want to use FUSE which can even set in /etc/fstab.

Windows

PuTTY which includes a (command-line) scp client.


PuTTY's configuration, a login shell, and editing with Vim.

There's a nice Windows scp client which is described at WinSCP. You should use this instead of ftp, and it will work to connect to most unix machines.

ExpanDrive (or Dokan SSHFS) lets you connect an sftp site to a drive letter on your Windows (or Mac) desktop.

If you would like to run X applications on your local windows desktop from a Unix machine using Putty and XWin32 please read this page.

Macs OS X

You can use Cyberduck, or MacFusion (with FUSE for OS X) to transfer files using a graphical interface. MacFusion integrates with the OS X finder and will freeze the desktop finder on 10.4 or earlier, so run MacFusion on 10.5 or higher. The shareware program Fetch is also available.

If you don't want to install software, or prefer using a command line, use the program /Applications/Utilities/Terminal to use the unix commmand line ssh and scp commands.

Public Host Keys

It is wise, although not strictly necessary, to pre-install public host keys. If you'd like to do so, or if you'd like to check if a machine's key has really changed, the public host keys for the various math systems are collected here: ssh_known_hosts2.