General Practice, Solo & Small Firm DivisionTechnology & Practice Guide

WINTER 1998 - VOLUME 1, NUMBER 2 << BACK TO TABLE OF CONTENTS

Understanding File Transfer Protocol

By Arlin P. Neser

The dramatic rise of the World Wide Web in recent years has made the Internet a phenomenon of every day life. Web browsers now make the Internet accessible to anyone who can simply “point and click.” You can “surf the Net,” download files, and send and receive e-mail in a flash. But this simplicity is deceiving. There is a lot going on behind the scenes as one travels throughout cyberspace. Interestingly enough, some of the same electronic tools created when the Internet was in its infancy still play a vital role in how it operates today. One of these tools is “FTP.”

What is FTP?

FTP is an acronym for “file transfer protocol.” Essentially, FTP is the basic Internet software tool that allows you to transfer files over the Internet from one computer to another. Files can be downloaded and uploaded using FTP. Files transferred via FTP can consist of software (including “executable” files), text, compressed files (e.g., “zip” files), and graphics.

Early on in the evolution of the Internet, when the main users were military, government, and academic institutions, FTP was created to allow researchers the ability to copy files from one computer to another. The impact of FTP was significant then and remains so today. Up until a few years ago, FTP accounted for more traffic on the Internet than any other service.

It is one of several tools that make up the “TCP/IP protocol suite.” Another commonly known tool of this suite is “telnet” which allows you to access a remote computer, view its contents, and manipulate it from afar. TCP/IP (which stands for Transmission Control Protocol/Internet Protocol) refers to the protocol or format that data are put into before being transferred over the Internet. TCP/IP provides a common layer through which data can be transferred over dissimilar networks and between computers using different operating systems. It is really the language that the Internet uses to communicate. TCP/IP is actually a combined set of protocols. It monitors and ensures that all the data sent from one computer is received by another computer. IP receives the data from TCP on one computer, breaks it up into packets, and ships the packets off to another computer where the packets are reassembled before being handed back over to TCP.

FTP has many uses. For example, it can be used to transfer a Webpage created on your desktop machine to the Web server that will ultimately host the Webpage. FTP can also be used to download software upgrades or new drivers from the Internet to your personal computer. Popular software programs like Cybermedia’s Oil Change (which assists you in identifying and locating updates to files already on your system) rely on FTP to retrieve and transfer files. FTP is also used to download shareware that you may want to try out. In addition, archives for electronic mailing lists are often stored on and are available through FTP sites.

Examples of FTP sites

Most organizations and companies that offer files (e.g., shareware, upgrades, and drivers) for download, make those files available on an FTP site. See, for example, the Microsoft FTP site which can be found at ftp.microsoft.com. While these sites and the files they contain reflect the organization or company that sponsors them, there are some FTP sites that tend to be more of an eclectic mix of all kinds of files containing text, graphics, and software. Some of these more eclectic sites include:

Electronic Frontier Foundation ftp.eff.org

Exploratorium ftp.exploratorium.edu

Finnish University and Research ftp.funet.fi
Network (FUNET)

Oak Software Repository oak.oakland.edu/pub

Internet Hunt Archives ftp.cic.net/pub/hunt/questions

Washington University wuarchive.wustl.edu
Graphics Archives

How Does FTP Work?

The computer that holds the files available for downloading via FTP is often referred to as an “FTP server” or “FTP site.” Access to an FTP site (and authorization to transfer files to or from that site) is often limited only to those users who can provide a previously obtained user name and password. However, there are “anonymous” FTP sites which allow general access to anyone. A visitor to an anonymous FTP site need only type in the word “anonymous” as the user name and an e-mail address (or some other string of characters) as a password to gain access.

FTP sites have addresses much like the URLs associated with Web- pages. However, instead of beginning with “http,” FTP sites begin with “ftp.” For example, the site for Compaq Computer Corporation is ftp://ftp.compaq.com. As with any Website, you can save the addresses for FTP sites accessed via your Web browser, in your Bookmark list or list of Favorite Places.

To actually transfer a file using FTP, first you activate the FTP software program that resides on your computer (often referred to as the “FTP client”). This could be a specific FTP software or even your Web browser (explained more fully below). Next you enter the address of the FTP server that contains the file you want to download. You will then be transferred to the FTP server. You will see a screen showing you a hierarchy of directories, folders, and files, much like what you see when you activate Windows Explorer in Windows 95.

Most FTP servers run under the Unix operating system. Common FTP-related directories have names such as “pub,” “mirrors,” “uploads,” and “incoming.” The most commonly used directory for files on an anonymous FTP server is the “pub” directory where many subdirectories and files for public use are stored.

Because of the popularity of certain FTP sites, many administrators also maintain “mirror” sites. These mirror sites contain directories that hold copies of files mirrored from other FTP servers.

Most FTP directories have an index file that contains a listing of all the other files on the FTP server. These indexes usually contain descriptive phrases that tell the content of each file and also may give some information about the file’s size and when it was uploaded to the server. The index file is often named something like “readme,” “readme.txt,” “00index.txt,” “dirmap.txt,” or simply “index.”

As you progress through the directories, you will eventually come to the names of files that you can download. As you look through the file names, you will be able to discern a lot about each file because of the three letter extension after the file name. The extensions on file names tell you many things about the file such as whether the file is an ASCII (text only) or binary file (image files, executable files including software programs, and word processing documents). It will also tell you the platform that you need to use in order to access the file and whether the file is compressed.

How Do You find files to download using FTP?

There are several methods for finding files located on FTP servers throughout the Internet. Many Websites have fill-in-the-blank search forms which allow you to enter information about the file you want to download. The Website performs a search and once the file is located, it employs FTP in the background to accomplish the download. Files located on FTP sites can also be found by using what are known as “Archie” and “Gopher.”

Archie. Archie is actually a database of several million file names with information about the directories and sites where the files reside. Archie is designed to locate specified files on anonymous FTP sites. There are many different variations of Archie (often referred to as “Archie servers”). A hypertext listing of these Archie servers can be found on the World Wide Web at . The hyperlinks at this Website will take you to user-friendly search forms that you can use to find a particular file to download using FTP. If you do not have a Web browser but still have access to the Internet, you can access one of the larger and more well-known Archie servers at Rutgers University by sending an e-mail message to archie@archie.rtugers.edu. In the body of your e-mail message type:

send mailto (do not add the brackets)

help

quit

As a reply, this Archie server will send you a list of Help commands that it recognizes. You then construct another e-mail message using the Help commands to tell Archie to find and return to you the anonymous FTP sites that are hosts for the file that you are searching for. Once you have this information, you can use FTP to connect to the host site and retrieve the file.

It should be noted that Archie servers know only the file name and not necessarily the contents of the file. So if you are searching for a file with a common name such as “Battlestation,” but with a file name “btlstn,” Archie will only know the file name “btlstn.”

Common extensions and what they signify

.txt ASCII or text only file

.wav or .au sound or audio file

.mid music file

.gif or .jpg graphics file

.hqx compressed file (Macintosh)

.zip compressed file (PC)

.gz compressed file (Unix)

.bmp picture file (PC)

.pict picture file (Macintosh)

Gopher. Another resource to locate FTP sites is “Gopher.” Gopher sites are particular computers or servers on the Internet that present information in simple lists called, “menus.” Individuals, organizations, and companies around the globe have set up more than 7,500 Gopher sites with information on almost every subject. Menu items usually have plain English names so you don’t have to worry about searching for files by cryptic names. Files referred to on a Gopher server are usually text-based but can also include pictures and sounds. A Gopher menu can link you to resources contained on that particular Gopher server or on other computers. Gopher menus usually point to other Gopher resources, but they can also point to FTP sites, Archie servers, and other Internet resources. You can search for Gophers relating to particular subjects by using the search engine on your Web browser. You can also start with one Gopher and then move through hyperlinks to other Gophers until you find the subject you are looking for. Gopher addresses are similar to Web and FTP addresses in that they follow a familiar pattern (e.g., gopher:// gopher.infor.com).

How do I transfer Files Using FTP?

To transfer files using FTP, you need a software program on your computer that has FTP functionality (the FTP client). Most Web browsers have basic FTP functionality built in, enabling them to act as an FTP client. Consequently, to visit an FTP site you need only type in the FTP site address. There are also stand alone FTP client software programs on the market which contain additional functionality and features. Many of these are designed to be used on machines using the Unix operating platform. But there are stand alone FTP programs for PCs (e.g., WS-FTP) and for the Macintosh (e.g. FETCH). Some of the main commercial online services like America Online also have FTP capability built into their Internet access software. For the average user who already has access to the Internet, functionality located in a Web browser is usually more than adequate to take care of transferring files using FTP.

How Do I Know When I’m Using FTP?

If you’ve ever obtained shareware or even freeware from the Internet you may have noticed that many of the places from which you can download these executable programs, are sites with addresses that start with the letters “ftp.” For example, using your Web browser, go to the download.com Website at . In the “Quick Search” box, type in the word “Wincopy” (which is a Windows shareware program for capturing screen images) and click on the “Search” button. At the next screen click on the “Wincopy 4.1” hyperlink. At the following screen, select the “Click Here to Download” hyperlink. At the next screen you will see a listing of site addresses that you can go to in order to download this program. Notice that the first two of these are sites whose addresses begin with the letters “ftp.”

Another example of where you may notice the functioning of FTP is when you download a file using the Netscape Navigator browser. As a file is being downloaded, the “Viewing Location” window appears on the screen. In that Window you will find listed the address for the site from which the file is being downloaded. Next time you download a file using Netscape Navigator, pay attention to the site address in the Viewing Window and see if it is in fact an FTP site.

Is There a Fee for Downloading Files Using FTP?

You should have free FTP software capability through your Web browser and through Windows 95. However, there are certain instances when you will incur a cost to download—for example, when purchasing software programs (both retail and shareware), when purchasing reprint rights of a magazine article, or when downloading materials from a legal publisher’s FTP site. In these cases, you will generally need to obtain advance authorization or a special user ID to even access the FTP site. If you use the Web to download files, you can generally obtain authorization through the Website by providing a credit card number or by making some other payment arrangement.

Does Knowing About FTP Really Matter?

Perhaps a detailed knowledge of FTP is not really necessary if you currently have access to the World Wide Web and all of its features to help you download files from the Internet. Most Web browsers can do at least basic FTP retrieval for you. However, knowing how to access FTP sites directly can help you cut down on the time it takes to download a file. It may also be helpful to know how to get to “mirror” FTP sites if the site you initially try does not give you access. In addition, knowing something about the workings of FTP and other Internet tools will give you a greater appreciation for the marvel that is cyberspace. n

Arlin P. Neser practices business, tax, estate planning, and probate law and is a consultant in the areas of legal technology and online services for attorneys. He is also the author of Law Office Guide to Online Courts . Mr. Neser can be reached on the Internet at arlinn@pacbell.net.

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