A Quick Introduction to FTP

Copying files from one computer to another is a pretty basic task, and copying those files over a network sure beats using floppies. When the network in question is the Internet, FTP (File Transfer Protocol) is the tool of choice for moving files. Is your computer connected to the UIC ADN-ii network? Then the ADN-ii's connection to the Internet can open up the world of FTP for you.

When you use FTP, the FTP software on your computer (your "local host machine") talks to FTP software on the computer you're exchanging files with (the "remote host machine"). FTP was originally designed for peer-to-peer file transfer -- you'd use it to copy a file from one computer or computer account belonging to you to another computer or account also belonging to you. When used in this way, you must have an active account on both computers and you must know each accounts' password. This is why you probably won't use FTP when you exchange files with your colleagues. They can't -- and you don't want them to -- read or write files in your personal storage space. (You'd probably use email instead, say, a MIME attachment with Eudora or Pine.)

But there are two important situations when you don't need an account and password on both computers to use FTP:

Most microcomputers don't have accounting systems; your being there to use it is proof enough that it belongs to you. Does this sound a little scary to you? Well, in most cases your microcomputer will not run FTP unless you're there to tell it to do so, so it'll be your local host machine and you'll decide which files you get or send. But newer network-aware operating systems like Windows 95 and OS/2 give you the option of running an "FTP demon". (A demon, a.k.a. daemon, is a program that runs in the background and provides its services on demand.)

Running an FTP demon on your desktop machine has its advantages -- mainly that you don't have to be at your PC to transfer files to or from it. But this is also a major and obvious disadvantage -- you can transfer files to and from your PC without being there, then maybe other people can too. You should be able to create an account for yourself on your FTP demon; guard its password as you would any other account's password. And be wary even if you don't run an FTP demon; FTP is by no means the only way to transfer files between machines on a LAN!

Anonymous FTP is the other, more important case where you don't need to have an account on the remote machine you're exchanging files with. There are many FTP anonymous server machines on the Internet; their purpose is to distribute files to the public. To get around the FTP requirement that "you have to have an account on the remote machine," these FTP servers have public accounts (usually a limited number so the server doesn't get bogged down) that anyone can use.

The login id for the public accounts on most anonymous FTP servers is anonymous, and guest is also common. The password can be anything, but most anonymous FTP service machines will ask you to enter your complete email address as your password. (So Ada Lovelace Byron's "password" would be her netid at uic.edu: adabyron@uic.edu.)

If you're new to the world of anonymous FTP, you'll probably find the Usenet/Netnews FAQ on anonymous FTP service useful. It's available on the Related Links page in the ACCC FTP Web pages. [Or type FTP in the Search box on the lower left of the ACCC home page and click Search. -- Ed.]

Want to Web-surf for anonymous FTP servers?

FTP is a perfect candidate for acquiring a GUI interface -- the FTP protocol says what functions should be provided by FTP software but not the actual commands to be used. FTP GUIs recommended by the UIC REACH experts are: For Macs, Fetch, the FTP client that comes with the Mac version of the Network Services Kit was very highly recommended. For Windows, check out "The Consummate Winsock Applications List" at http://www.midwest.net/software/cwsapps/ctism.html (select FTP / Archie / Finger); ws_ftp was specifically recommended. {These days, Ws_FTP is included in the Win95 Network Services Kit. --Ed.] For OS/2, you can get VxFTP from the IBM Hobbes OS/2 archives; http://www.columbia.edu/~chs11/hvm.html is a good place to start. (VxFTPis in the /network directory.) And for X Windows, xftp from Lawrence Livermore Labs, http://www.llnl.gov/liv_comp/xftp.html

So why use FTP the old-fashioned way -- with FTP commands or software -- rather than the new way on the Web? Well, the Web is a good way to explore anonymous FTP sites to find the ones you're interested in -- good for both you and for the FTP site itself. When you connect to an FTP site via its URL, your browser connects only briefly, just long enough to get a directory list, so you don't tie up the FTP connection while you're browsing through its directories. And unless you're using an FTP GUI, your Web browser will display the FTP server's directory lists in a much more convenient manner.

So, sure, if you're out there surfing the net to find the anonymous FTP site that has what you're looking for, use your WWW browser. But once you know what "remote machine" you'll be using, whether it's an anonymous FTP site or your own ADN account, you might find that it's better to connect to it using FTP, if only because after you connect to the remote FTP server, you'll stay connected while you transfer all the files you want. This is particularly useful with anonymous FTP servers; they can be very busy, particularly during the day, and you might have to try several times before you make a connection. And you might find it easier to control the mechanics of the transfer using FTP or an FTP GUI.

help cmdname

You can also request help for the remote FTP demon's commands. For example, the FTP demons on the ADN UNIX machines support a group of useful UNIX-specific commands; to see a list when you're FTPing to one of them, enter: site help
For help on one of these site commands, enter:

site help cmdname

Comments are appreciated; send them to
Judith Grobe Sachs, judygs@uic.edu