This is an archive page !!!


Publicly Accessible Files

The transfer of publicly available information is one of the most widespread uses of the file transfer capability on the Internet. Many of the organizations connected to the Internet provide openly accessible file transfer sites with information that anyone can obtain (or get). Files are stored in "open" or public areas of computers, and you can access them by using the file transfer program to connect to those systems. A file that is "available via anonymous FTP" is publicly available, and you can connect to a public archive computer and use the file transfer program to copy it to your own system.

Remember that you need a login name and password to be allowed into a computer. For publicly accessible files, the login name is anonymous and the password can be anything, although it's a good idea to type your email address. (Sometimes guest is the specific password required.) Once you master spelling anonymous, you can roam around the public storage areas on computers on the Internet just as you explore public libraries.

Not every computer on the Internet makes public file storage areas available, but there are thousands of systems that offer gigabytes and gigabytes of "published" information. (One recent count put the number of publicly available files at well over 2.2 million.) These sites are making available electronic books, public domain software, and graphic images--lots of amusing, useful, and interesting stuff. (Check the Appendix for instructions on obtaining a list of anonymous FTP sites.)

Navigating around different computer public storage areas takes some practice. As was mentioned before, there are different kinds of computers out there, and some present their electronic folders a bit differently. Many systems provide README files that explain what files are available or anything you might need to know about the collection of files. You simply transfer the README file: get README. (There's no standard name for an information file; they may be called 00README, or readme, READ.me, INFO, INDEX, and so forth. You can usually tell what file will provide information when you get a directory listing.)

Let's transfer a file called Special Internet Connections by Scott Yanoff. He has compiled a sort of travel guide of interesting places to visit on the Internet. (Of course, you should read the rest of this chapter first to understand how to access many of the sites listed.) Special Internet Connections is available via anonymous FTP on the computer csd4.csd.uwm.edu, in the directory pub, with the filename inet.services.txt. Also, take note that this is a text file (the extension ".txt" gives this away). This bit of information will come in handy, as you'll see in a moment. Not all filenames have an extension that specifies file type, but many do. See the "Common File Formats on the Internet" table for a listing of the more common ones.

The example below will not walk you through executing a directory listing (using the dir command), but remember that you can use that command to see what other files are available. If you wish to rename the file as you're transferring it to your system, the command is get remote-file new-file-name. Here's what you'd see on your screen (the commands you would type on many systems are shown in bold):

sport}ftp csd4.csd.uwm.edu
Connected to csd4.csd.uwm.edu.
220 csd4.csd.uwm.edu
FTP server (Version wu-2.1c(3) Fri Oct 29 13:50:21 CDT199.
Name (csd4.csd.uwm.edu:tparker): anonymous
331 Guest login ok, send your complete e-mail address as password.
Password:
230-University of Wisconsin-Milwaukee FTP server
230-Local time is Sun Jun 5 14:05:27 1994
230-
230-If have any unusual problems, please report them
230-via e-mail to help@uwm.edu.
230-
230-If you do have problems, please try using a dash (-) as the
230-first character of your password -- this will turn off the
230-continuation messages that may be confusing your ftp client.
230-
230-Please read the file Policy
230- it was last modified on Mon Dec 6 08:06:40 1993 - 181 days ago
230 Guest login ok, access restrictions apply.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ascii
200 Type set to A.
ftp} cd pub
250-This directory contains public files for anonymous users. Files may
250-be read, but not written (use "/incoming" for writing new files).
250-
250 CWD command successful.
ftp} get inet.services.txt
200 PORT command successful.
150 Opening ASCII mode data connection for inet.services.txt (48244 bytes).
226 Transfer complete.
local: inet.services.txt remote: inet.services.txt
49151 bytes received in 0.81 seconds (59 Kbytes/s)
ftp} quit
221 Goodbye.
sport>

After connecting to this computer, one of the first messages you get before the ftp} prompt is "Using binary mode to transfer files." This means that the system is assuming you are transferring non-text files-- images, software, or compressed files, for example. If you know you're transferring a text file, then immediately set the transfer type to "ascii" by typing the command ascii. If you don't do this, your file may appear funky because the line terminators might not transfer correctly.

Non-text Information

If you're planning on transferring non-text, then you need to do a binary transfer. Files that have been compressed are binary files, as are software programs. A compressed file is basically "dehydrated"--or squeezed--to conserve disk space and also to make the transfer time faster. As was noted above, some systems automatically assume you're doing a binary transfer, but if not, you can set this mode easily by typing binary before you type get or put to transfer a file. This tells the system that you're moving a compressed, or non-text, file. Typing ascii will put you back in text mode.

Obtaining Software

Software archives are all over the Internet. The Washington University Public Domain Archives is a great place to start, with a boatload of public domain and shareware software for the Amiga, Apple II, Atari, CP/M, DOS, GNU, Macintosh, Sun, TeX, Unix, VMS, and X Windows systems. There's so much on this system that it's advisable to obtain any README files in each directory to learn about what's available when you're exploring. If you want to check out this system, type ftp wuarchive.wustl.edu and login as anonymous, and use your email address as a password. (Don't forget to specify binary transfer for software!) Before you stock up on software, read the section on security in Chapter 5. And check the Appendix for some other places to find software.


guiltware /gilt'weir/ n. 1. A piece of freeware decorated with a message telling one how long and hard the author worked on it and intimating that one is a no-good freeloader if one does not immediately send the poor suffering martyr gobs of money. 2. Shareware that works.

Source: The New Hacker's Dictionary, edited by Eric S. Raymond, with assistance and illustrations by Guy L. Steele, Jr. 1991 Eric S. Raymond. Published by The MIT Press, Cambridge & London, 1991. Reprinted with permission.


File Formats

As was mentioned earlier, certain files work only on certain computers, so it's good to have a little knowledge of the types of files, how to know which is which, and what programs, if any, you'll need to use the files.Macintosh programs are sometimes in the BinHex (ASCII) format. Once downloaded and un- BinHexed, the files will most likely have to be uncompressed. Because PC files and programs are usually in compressed format, they will almost always have to be uncompressed with a utility like PKZIP or StuffIt after being downloaded.

The chart opposite shows some of the more common file types you'll see--sounds, graphics, and compressed--the programs they work with, and how you should transfer (ASCII or binary mode) each of them. A document available via anonymous FTP explains most file compression, archiving, and text- binary formats, and tells where you can get software to convert these various formats. This regularly updated document is maintained by David Lemson, and can be obtained via anonymous FTP from ftp.cso.uiuc.edu, in the directory doc/pcnet (type cd doc/pcnet), filename compression.


Common File Formats on the Internet
		File Program 	File 				Transfer
Ext		Name		Type		Computer	Method

.bin MacBinary binary Mac binary .cpt Compact Pro compressed Mac binary .sit StuffIt compressed Mac binary .hqx BinHex 4.0 encoded Mac ASCII .hqx BinHex 5.0 encoded Mac binary .sea self-extracting binary Mac binary .qt Quicktime video Mac/PC binary .arc ARC, PKPAK compressed PC binary .arj ARJ compressed PC binary .lzh LHArc compressed PC binary .pak PAK compression PC binary .voc Soundblaster sound PC binary .wav WAVE sound PC binary .zip PKZIP/InfoZIP compressed PC binary .zoo zoo compressed PC binary .snd NeXT audio file sound Unix binary .Z compress compressed Unix binary & uncompress .gz GNU Zip compressed Unix binary Archiver .tar tar archive Unix binary .xbm X-Bitmap image Unix (X) binary .au Sun Ulaw audio Unix/any binary .rs Sun raster file image Unix (X) binary .ps PostScript page Any ASCII or description binary .gif GIF graphics Any binary .txt text text Any ASCII .uu/uue uuencode encoded Any ASCII & uudecode .jpg/.jpeg JPEG image Any binary compression .tif TIFF image Any binary .mpg/.mpeg MPEG video Any binary compression


Obtaining Information via Electronic Mail

If you don't have direct access to the Internet, are you forever cut off from publicly available files? No-- there are other ways to get files. If you are in a situation in which you can't interactively use FTP, you might want to check out the alternatives explained in this section.

Using what's called an info-server, or an email-server, you can get publicly accessible files by just sending an email message with a command (such as send info). One command that should always work is help. The message is sent to a server that processes the order and emails the requested files back to you within a few minutes or, usually, by the next day.

That's all there is to it.

Many anonymous FTP sites also provide an email service for access to their own files. Some computers, however, will act as general purpose email/FTP translation servers. This means that the files don't have to exist on those computers--you can send orders for any publicly available files, no matter what computer they're on. These are known as FTP-by-email servers; they transfer the files from the computers they reside on, and then email them to you.

One FTP-by-email server is ftpmail@pa.dec.com. Send an email message to that address, with a one-line message in the body: help. (Don't worry about the Subject--anything will do.) You will be sent a help file telling you what commands to use to obtain files. Another server is BITFTP, named because it processes file requests from BITNET users. If you're on BITNET, send email (command help, initially) to BITFTP@PUCC or bitftp@pucc.princeton.edu. You should receive a help file explaining how to use BITFTP. (The Appendix lists some other FTP-by-email servers.)


Faster Than Braille Mail

Like a lot of undergraduates these days, Tina Ektermanis roams the Internet for research and recreation. From the terminal in her dorm room at Northwest Missouri State University, she uses all the standard tools and utilities--email, FTP, Gopher, news, and IRC. The Internet doesn't know that she's blind.

Ektermanis, a computer science major, uses voice-synthesizing hardware to read the output from her screen. The ASCII text she brings home from the Net is easier to scan and search than the braille and cassette sources she uses offline in her studies, and the USENET news is far more timely. Logging in to GENIE's forum for disability issues allows her to communicate seamlessly with other handicapped Internauts, particularly the deaf, whose signing she can't interpret in real-life.

She bumps against the limits of her system only when she crosses a language barrier--a MUD game in Stuttgart made her voice synthesizer crazy--or encounters ASCII art. A rose is not a rose on her terminal-- it's a maze of audible punctuation marks. Otherwise, she sails along like any other student on the Net. "When I'm home on vacation," she says, "I really miss it!"


FINDING RESOURCES AND FILES

So many resources and public archives are available that it's impossible to cover everything, and people all over the world are constantly cooking up interesting new offerings. There are lots of resource directories, guides, lists of public FTP sites, and lists of online library catalogs that can help show you the way to important resources. Usually they're maintained by volunteers and made available without cost via anonymous FTP, posted regularly to certain mailing lists and newsgroups, or in hardcopy form for a nominal price. The Appendix lists the more popular guides. You can also learn about new resources through mailing lists and USENET postings, or by word of mouth.

Uniform Resource Locators

As our lives seem to become increasingly complex, finding key pieces of information, both in your office file cabinet and on your computer's hard drive, can be difficult, especially around tax time. You've probably been heard to mutter more than once "I need a new system."

As the Internet has matured, the different applications and resources have grown up too, and the need for a new resource naming system has become apparent. Pick up any documentation or guide describing the grea1t Internet resources you can access, and chances are you'll see a lot of different ways of describing how to find that information. A new naming methodology for locating information has surfaced recently and, as of the writing of this updated edition, is currently still in development. The chances it will be adopted universally are very good.

The naming system is called Uniform Resource Locators (URL), and it applies not only to "stuff" that can be accessed via current information retrieval and discovery tools, but to any applications that are developed in the future. The URL naming system can be used by people when referring to a particular resource (in an email message, resource guide, or book), and by computers when giving directions to an application on how and where to access a resource. As with anything in the computer and networking industry, the URL system can get quite complicated. This section explains some of the more common ways you'll see it used. The basic anatomy of a URL is as follows.

First Part. The first identifier you see refers to the type of application used to access the information, for example, FTP, Gopher, and so on. This identifier is always followed by a colon.

Second Part. For Internet applications, the URL designation begins with a double slash, "//", and then specifies information needed to find and access the host where the resource resides. This includes a user login name and password (if needed), the domain name of the host, and a port number (if needed). Usually, what follows the double slashes is just the hostname. You'll know if a port number is referenced because following the hostname there will be a colon and then a number. That number is the port number. If you don't see one, you don't have to worry about it.

Third Part. Once you've accessed the host, the resource needs to be located on that host. This part describes the "path" of the information.Here's an example URL:

ftp://nysernet.org/pub/resources/guides/surfing.2.0.3.txt

This describes an FTP site, nysernet.org, and the directory

path /pub/resources/surfing.2.0.3.txt. (The file listed above is an article called "Surfing the Net.") To retrieve this file, use ftp to connect to the host:

ftp nysernet.org

Then change directories:

cd /pub/resources/guides

And then get the file:

get surfing.2.0.3.txt

Here's another URL:

gopher://rugcis.rug.nl:70/

This is the URL describing a Gopher server for the Netherlands (Gopher is described below). In this example, a port number is specified: 70. In this case, 70 happens to be the default port number for the Gopher application, so you usually don't have to type it in. But if you did, here's how you could access this resource:

gopher rugcis.rug.nl 70

URLs can also describe USENET newsgroups. Here's a USENET URL:

news://rec.arts.marching.drumcorps

Keep in mind that the preceding description is only meant to get you started in learning how to understand a URL. The URL system is very flexible, so there are many ways to use it. See the Appendix for pointers to the URL standards documentation.

Backward Forward Copyright © 1994 by Tracy LaQuey and Editorial Inc.


[ OBS - Home | OBS - The Bookshelves | The Internet Companion ]