Department of
Physics & Astronomy


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P&A Computer System
Remote Access

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 ( 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:
  • 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.
Once you have obtained an Internet connection, it can be used for web browsing, ssh, and sftp.

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	
	th123-22	th123-23
	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:
  • 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.
SSH is included in many of the newer operating systems, such as Linux and Mac OS/X. If your system does not have SSH, a free download, called SshClient, is available for most platforms at 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 information. MS-Windows users will also need an X-Windows emulator, such as XWIN32.

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 &
	[1] 23983
	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 called 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
From MS-Windows, just invoke SshClient, and select File Transfer. You can read from's documentation about other options in the SSH suite.