198 lines
7.9 KiB
Plaintext
198 lines
7.9 KiB
Plaintext
Questions & Answers about anonymous ftp
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odin@pilot.njin.net
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January 5, 1990
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This is a document I pieced together from various
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sources. It is not a definitive guide to ftp, but just
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something to give a novice a general idea of what it is and
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how to do it.
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What is FTP?
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FTP (File Transfer Protocol) allows a person to
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transfer files between two computers, generally connected
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via the Internet. If your system has FTP and is connected
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to the Internet, you can access very large amounts of
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archives available on a number of systems. If you are on
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Bitnet or a UUCP host, you should look for servers that work
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through the mail. A good source of information on archives
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in general, is the Usenet newsgroup comp.archives.
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What is Anonymous FTP?
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Many systems throughout the Internet offer files
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through anonymous FTP. These include software, documents
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of various sorts, and files for configuring networks.
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Archives for electronic mailing lists are often stored
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available through anonymous FTP. Note that all this is
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subject to change.
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Commands
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All the normal FTP commands may be used to retrieve
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files. Some FTP commands are the same on different comput-
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ers, but others are not. Usually, FTP will list the com-
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mands if you type "help" type a question mark (?). Also,
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your computer's help command may have information about FTP.
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Try man ftp or man ftpd.
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Some useful commands available on most systems include:
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get copy a file from the remote computer to yours
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ls/dir list the files in the current directory
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cd Change directory
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binary Switch to binary mode. For transferring binary files
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ascii Switch to ascii mode. Ascii mode is the default mode
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Procedure
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Anonymous ftp is a facility offered by many machines on
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the Internet. This permits you to log in with the user name
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'anonymous' or the user name 'ftp'. When prompted for a
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password, type your e-mail address -- it's not necessary,
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but it's a courtesy for those sites that like to know who is
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making use of their facility. Be courteous.
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You can then look around and retrieve files. (Most
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anonymous ftp sites do not permit people to store files)
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1
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Typically, a directory called 'pub' is where the
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interesting things are stored. Some sites will have a file
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with a name like ls-lR, that contains a complete list of the
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files on that site. Otherwise, you can type ls -lR and get
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such a listing -- for some sites, this can take a LONG time.
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Usuually, files are grouped in archive files, so you
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don't have to get many small files separately. The most com-
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mon archival file format for the Internet is tar. Occasion-
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ally, people use shell archives (shar) instead. tar archives
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can be unpacked by running the tar command -- you may want
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to first do a 'tar t' on the file to see what it contains
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before unpacking it. Be careful when unpacking shell
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archives since they have to be run through the Bourne shell
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to unpack them. (The simplest way is to use the unshar com-
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mand)
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Files are often stored compressed -- for Unix, the most
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common scheme is the compress program, indicated by a .Z
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suffix on the file name. Sometimes, people use programs
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like arc or zoo, which are combined archival and compression
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formats. (There are probably other archival formats as well
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- talk to the systems staff if you encounter them and don't
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know how to deal with them)
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When retrieving non-text files, you must use binary
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mode, otherwise the file gets messed up. To do this, use the
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'binary' command. (It's safe to set this for text files. If
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the site at the other end is non-Unix, you may need to use
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some other mode -- see the documents for that site and for
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ftp)
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The simplest way to initiate FTP would be to give the
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command 'ftp <system-name>', where <system-name> is the
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remote system you are connecting to, either a name (wsmr-
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simtel20.army.mil, if you have an entry in /etc/hosts or are
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accessing a Domain-name Server) or the InterNet address
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(26.2.0.74, for Simtel20). After a short wait, you will be
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prompted for your username. If you do not have an account
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on the remote system, some systems allow you to use
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'anonymous'. This gives you a restricted access path.
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You would then be prompted for a password. Some sys-
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tems will tell you to send your real identity as the pass-
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word. What you type doesn't matter, but it is suggested to
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give your mail address. Other systems need a password of
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'guest', or something similar.
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After that, you should receive the FTP prompt (usually
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ftp>), and now have access. You can get a directory of
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files be giving a 'dir' command, or if the remote system is
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Unix-based, 'ls -l' will give the familiar output. On Sim-
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tel20, there is a file available in the default anonymous
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ftp directory that explains what Simtel20 is, and where
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files are located. The name is 'SIMTEL-ARCHIVES.INFO.nn,
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where ".nn" is a file generation number. You don't need to
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specify the file generation number when requesting the file.
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In fact, it's better not to because you will always get the
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latest generation that way.
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9
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9 2
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Unix systems will all have the familiar directory
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structure, and moving around is done with the familiar 'cd'
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or 'cwd' command. TOPS-20 systems have a different struc-
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ture, but movement is still accomplished with the 'cd' com-
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mand.
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Different systems have different organizations for
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their files, and the above example is just the way I have it
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set up. By 'poking' around other systems, you can learn how
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their files are set up, and zip around much faster. Note,
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however, that FTP will not allow you outside the FTP 'root'
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directory, usually ~ftp on most systems. So, poking about
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the entire system is not permitted.
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File types
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These are the common Unix file types:
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Suffix FTP Type
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.Z bin compress
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.arc bin ARChive
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.shar ascii SHell ARchive
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.tar bin Tape ARchive
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.uu ascii uuencode/uudecode
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.zoo bin Zoo
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However, there are more file compression types than those
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listed above. Below is a some mail I received recently
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describing how to get a document describing a much larger
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set of file compression methods and the programs used.
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----
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>From mjones@ux1.cso.uiuc.edu Wed Aug 15 17:42:33 1990
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Date: Wed, 15 Aug 90 16:42:51 -0500
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From: Mike Jones <mjones@ux1.cso.uiuc.edu>
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To: odin@pilot.njin.net
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Subject: additional info for ftp.list header?
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Hello, my name is Mike Jones. I am a student working at the University of
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Illinois. I have been compiling a list of file compression and archiving
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techniques. My supervisor suggested I ask you if this might be worth
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mentioning in the header of the ftp.list. What it shows is the names of
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all file compression/archiving methods known to us and the programs to
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undo the compression/archive on PC, Mac, Unix, VM/CMS, and Amiga systems.
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This could be helpful to people new to ftp that don't know how to unpackage
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the file they have just transferred. The list can be seen via anonymous ftp
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at: ux1.cso.uiuc.edu
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cd doc/pcnet
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get compression
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get compression2
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Thanks you for your time and consideration.
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mjones@ux1.cso.uiuc.edu
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9
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9 3
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==== <g FTP> 10 links in glossary topic
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==== <g ANONYMOUS> 2 links in glossary topic
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