The Best Internet Programs/BESTINTERNET.bin/latest/roadmap/map13.txt

Internet Message Format | 1995-02-08 | 10KB

Date:         Tue, 7 Feb 1995 10:11:56 -0600
From: BITNET list server at UA1VM (1.8a) <[e-mail]>
Subject:      File: "MAP13 LESSON"

MAP13: FTP (PART ONE)


     "The desire of knowledge, like the thirst of riches, increases
      ever with the acquisition of it." -- Laurence Sterne, Tristram
      Shandy


Welcome back to the third week of the Roadmap workshop! I hope
that you are having as much fun participating in this workshop
as I am having teaching it! :)

Last week we used a tool called "Telnet" which allowed us to access
remote computers and run programs on those remote computers.

This week we are going to use a tool called "File Transfer Protocol"
(or "FTP") which will allow us to access remote computers and retrieve
files from these computers. Actually, it is probably more accurate
to say that we will be using "anonymous" FTP, but I'll explain that
in a minute.

What sort of files are available through FTP?  Well, "hundreds of
systems connected to the Internet have file libraries, or archives,
accessible to the public. Much of this consists of free or low-cost
{computer} programs for virtually every make of computer. If you
want a different communications program for your IBM, or feel like
playing a new game on your Amiga, you'll {probably} be able to get it
{using FTP}."

"But there are also libraries of documents as well. If you want a
copy of a recent U.S. Supreme Court decision, you can {get a copy
using FTP}. Copies of historical documents, from the Magna Carta to
the Declaration of Independence are also yours for the asking ...
You can also find song lyrics, poems, {and} even summaries of
every {Animaniacs} episode ever made. You can also find extensive
files detailing everything you could possibly want to know about
the Net itself" (1)

Before we get too in-depth into FTP, I think that now is as good
a time as any to quickly review the client/server relationship
that I briefly mentioned in lesson three (MAP03: Levels of Internet
Connectivity).

"Client" is just another word for a program running on your
service provider's system that enables you to talk to, and get
stuff from, distant computers. The client on your service provider's
system takes your commands and turns them into requests for information
from programs -- "servers" -- running on other, distant computers.

The client/server relationship allows you to TELNET into remote
computers and run programs on those remote computers, and it also
allows you to use FTP to get files from remote sites.

The client/server relationship is also what makes my job as an Internet
trainer quite difficult. While all of the FTP clients out there do the
exact same thing, they all use different commands to do it.

Fortunately, if you can understand the basics of what happens during
an FTP session, the commands -- no matter what client you are using --
are pretty easy.

The basic steps in an FTP session are:

     1. Start-up your FTP client
     2. Give your FTP client an address to connect to (and, just
        like TELNET, step one and two can be combined into one
        easy step).
     3. Identify yourself to the remote site
     4. Give the remote site your password
     5. Look around the directory for files
     6. Change Directories
     7. Set the transfer mode (optional)
     8. Get the file(s) you want
     9. Quit

The best way to understand what is going on is to look at a sample
FTP session. The University of Alabama's connection to the Internet
is through SURAnet (a large regional network), so I'm going to FTP
to them.

Before I do that, though, there are three things that I need to
emphasize:

     1. FTP requires a heck of a lot of resources, both on your
        system and on the remote system that you are accessing.
        Because of this, FTP sessions should only be run during
        non-working hours (usually 6 PM to 6 AM local).

        I realize that this constraint is going to be a difficult
        for those of you who are reading this at work, and who only
        have Internet (and FTP access) through your employer. However,
        as responsible Internet citizens we have to remember that
        the FTP sites are providing us FTP access out of the kindness
        of their hearts. If we take advantage of this kindness, and
        access various FTP sites during working hours, those FTP
        sites may decide to close their doors to the public ... and
        then EVERYONE loses.

     2. In light of what was said in #1, please do not flood SURAnet.
        Later this week I will post a list of FTP sites that you
        can visit (much like the TELNET list I posted Friday).
        Until I post that list, just sit back and enjoy the show :)

     3. Since this lesson is already over 100 lines long, I hope that
        you won't mind if I break this FTP lesson into two lessons.
        The first lesson will be today, and I'll finish tomorrow.
        This will mean that we will end this lesson in the middle
        of our sample FTP session, but it will also mean that this
        lesson won't be the size of a small book :)

Starting an FTP session is pretty easy. For most of you, all you
have to do to start-up your FTP client is type

          ftp

on you system's command line (or, if you are in a Windows or Mac
environment, double-click on the FTP icon).

From there, you would give the client an FTP address to connect to.

Like TELNET, however, there is a way to combine these two steps into
one, easy step. For most of you, to access your FTP client and give
your client an address to hook up to, all you would have to do it
type the command

          ftp <site address>

and replace <site address> with the address of the FTP site that you
want your client software to access.

In our example, the SURAnet FTP address is ftp.sura.net, so I would type

          ftp ftp.sura.net

to start an FTP session. (Note that the second "ftp" is part of
SURAnet's FTP address. If I wanted to ftp to info.umd.edu, I would
type "ftp info.umd.edu"; if I wanted to ftp to lcs.mit.edu, I would
type "ftp lcs.mit.edu").

Once I hit the enter key, the following appears on my screen:

   ftp ftp.sura.net
   Connecting to ftp.sura.net 128.167.254.179, port 21
   220 nic.sura.net FTP server (Version wu-2.4(1) Fri May 20 10:20:58
   EDT 1994) ready.
   USER (identify yourself to the host):

The second line tells me that my system is connecting to ftp.sura.net
(and even gives me the IP number for ftp.sura.net), the third line is
some automatic information from SURAnet, and the bottom line is asking
me to log in.

If I had an account on the SURAnet system, I would enter my SURAnet
user ID. But, since I don't have an account on this system, I have
to find another way to access the system. ;)

This is where the "anonymous" FTP I mentioned earlier comes in :)
The other way to access some FTP sites -- at least those FTP sites
that allow outside access -- is to use the userid "anonymous".
By using the name "anonymous", you are telling that FTP site that
you aren't a regular user of that site, but you would still like to
access that FTP site, look around, and retrieve files.

So, where it says USER, I type the word

          anonymous

hit enter, and cross my fingers. If SURAnet does not allow anonymous
access, I'm about to find out :)

   >>>USER anonymous
   331 Guest login ok, send your complete e-mail address as password.
   Password:

COOL! Its going to let me in. All I have to do is give the site a
password.

Out of politeness to the FTP site, if you login as "anonymous", you
need to use your full Internet address as your password. This helps
the FTP site keep track of who has visited its site.

So, since it wants my password, and since the password for any
anonymous FTP session is my full Internet address, I type

          [e-mail]

(Stop laughing -- p-crispy-one is *NOT* funny!!). Once I hit enter,
my screen fills with the following:

   >>>PASS ********