Computer Science SSH and SCP
Using Secure Shell (SSH) and Secure Copy (SCP)
Telnet and FTP are protocols designed to allow you to remotely connect to
a machine and either run programs on them or copy files to and from
them. They work reasonably well. However, many people are
unaware that they both send your password, user name, and everything you
do over the network in cleartext, or unencrypted form. This means
that anyone on the network between the host computer and the machine you
are connecting from could read your username, password, email, files,
ect. in realtime during your telnet session.
With this information, they can log into the system as you. They can send
email as you, read your mail, your files. Worse, they can launch attacks
on other systems as you. This can get you into an enormous amount of
trouble. In business, it could result in the loss of important
So what do I do?
Secure Shell (SSH) is an encrypted protocol designed as a replacement for
telnet. A companion program, Secure Copy (SCP), allows you to transfer
files to and from computers securely. All of our UNIX remote access
computers accept SSH and SCP connections from anywhere in the world.
SSH is easy. Download PuTTY, a
Windows SSH client. We have a whole page dedicated to helping you get
started with putty here.
Simply download and run putty.exe. Make sure the radio button for
SSH is selected (NOT the telnet option) and type in the address of the
machine you want to connect to. (for example, wirth.cs.uakron.edu)
You will be prompted for your username and password, and then the login
will proceed exactly as you are used to for telnet. It is completely
transparent to the user.
Copying files with SCP
The easiest way to use SCP to securely copy files to the UNIX network from
the wireless network or your home is to use WinSCP. This is a graphical interface that
allows drag and drop file copying similar to many of the FTP clients
available. Although the application is currently listed as being in Beta,
it works very well. We use it here every day.
You can also use command line mode secure copy in Windows if you
prefer. . Download pscp.exe
from the putty
site above. It must be run from the command line, unless you use a GUI
interface. We are testing one and will include it here shortly.
To copy a file from your home computer to a remote host:
pscp sourcefile username@machinename:path/file
pscp a:\index.html firstname.lastname@example.org:public_html
To copy a file from a remote host to your home computer:
pscp username@machinename:path/filename localfile
pscp email@example.com:public_html/index.html a:\index.html
Note that in both cases, you do not need to enter the full path to the
file - the program starts you at your home directory.
Also note you can copy files from one UNIX system to the other using
scp. The syntax is the same as above, except the program name is scp
rather than pscp. Type 'man scp' for more details.