P&A Computer System
These instructions are intended to enable users of the Physics and
Astronomy Department computer system to use the system from locations
other than the Department computer room (TH 123).
This requires a computer with network access, either direct
(via DSL, cable internet, or other direct connection)
or modem access through the University modem pool.
At present, email to a P&A account (firstname.lastname@example.org)
can be accessed by logging onto the Department system.
This can be done using ssh, or from a web browser.
Also available are Web Mail,
and IMAP connection.
Files can be accessed using secure FTP (sftp).
(Note that both TELNET and FTP accesses have been disabled at our site,
as they are vulnerable to hackers. Ftp clients are still available in
order to access other sites which do not support sftp.)
Once logged on, all graphical applications can be run remotely.
Getting Internet Access
To log onto the Department computer system, you must "come in over
the internet." This must be done in a way which ensures secure
authentication, where your password cannot be stolen by someone
listening in to network traffic. Getting on the internet can be
achieved in the following ways:
Once you have obtained an Internet connection,
it can be used for web browsing, ssh, and sftp.
- Direct network connection.
Throughout the campus, and at many workplaces, the network is wired
directly to computer stations.
A computer connected this way is always "on the internet."
- Internet Service Provider (ISP) account.
An ISP can provide you with an Internet account. Your connection
can be DSL, TV Cable, or modem dial-up.
Through a high-speed modem, the first two services provide a direct,
constant connection to the internet.
A dial-up modem account is the slower and least expensive option,
using a modem attached to your existing phone line.
- Connection through the University modem pool.
The university provides free internet service
to students, faculty and staff. This requires
an account on the
University system (also free), a modem on your computer, and an
available telephone line.
Logging onto P&A Computers Remotely
Next you must connect to one of the Linux machines in TH 123 and supply your
user name and password.
Their host names are:
th123-11 th123-12 th123-13
th123-32 th123-33 th123-34
As mentioned above, for security reasons, our computers
do not accept connections to programs such as telnet which transmit
your unencrypted passwd over the Internet.
Here are ways to do log in:
SSH is included in many of the newer operating systems, such as Linux and
If your system does not have SSH, a free download, called SshClient,
is available for most platforms at ssh.com.
Go to one of their download sites to download.
An evaluation copy and a non-commercial version are available.
Refer to Getting and Using SSH for more
MS-Windows users will also need an X-Windows emulator,
such as XWIN32.
- A web logon is available on our system.
- From a Unix machine connected to the net, run the application ssh.
- For a MS-Windows installation, obtain an ssh client program.
Click on the file and it will self install. Run SshClient.
A remote logon on a P&A Unix/Linux system allows you to do any number
of useful things: read mail using pine, run IDL, MatLab,
and Mathematica, edit web pages, develop software,
even run MS-Windows-based applications.
Refer to Unix Platforms for detailed information
about using the P&A Unix Network.
Remote Graphics Support
Running remote graphics-based programs requires special configuration.
Often, the SSH connection will automatically configure the connection to work.
To see, enter the command
quark:bland% xclock &
If a clock face pops up on your screen, you are set up properly;
you can run remote graphics applications, and they will display locally.
(You can type
q in the clock window to make it disappear.)
On a bad-karma day you may get the following error message:
quark:bland% xclock &
quark:bland% Error: Can't open display:
If this happens, refer to
Remote Graphics Configuration.
Remote File Transfer
Now that you have SSH installed, you also have remote file transfer capability.
The standard file-transfer program, FTP, is now in disgrace due to its security
problems (unencrypted password exchange).
But the SSH utility described above comes with a secure file transfer program
sftp which is very elegant, easy to use, and powerful.
The SshClient for MS-Windows has analogous functionality.
From a Unix/Linux machine you can connect to a P&A host with sftp
much as you would establish a login connection (below).
Invoke sftp, and use your P&A login name and password:
homesys% ftp quark.sfsu.edu
From MS-Windows, just invoke SshClient, and select File Transfer.
You can read from
ssh.com's documentation about other options in the SSH suite.