FTP GUIDE #1
Source#1
Article
about FTP
Source #2:
FTP Guide #2
Contents
1.0 What is FTP?
2.0 What is FTP used
for?
3.0 What is a file archive?
4.0 How does FTP connect to an
Anonymous FTP site?
4.1 Finding a Domain Name or IP
Address
5.0 Where are Anonymous FTP sites
located?
6.0 How do I invoke FTP on
ROHAN?
7.0 How do I open a new
FTP session?
8.0 What is Binary vs. ASCII?
9.0 What are compressed
files?
10.0 What are tar files?
11.0 What microcomputer
software offers FTP?
12.0 What FTP commands are
available?
1.0 What is FTP?
FTP is an acronym for File Transfer
Protocol and one of the programs using the TCP/IP (Transmission Control Protocol/Internet
Protocol) suite. So, what is a protocol? A protocol is a set of rules that
govern data interaction on a network. FTP is the rule set that allows files to
be transferred between different kinds of computers, without concern for their
operating system or how they are connected. But, the local and remote computers
must either be able to establish a physical connection, or both must run the
TCP/IP protocol and be connected on the Internet.
Return to Contents
2.0 What is FTP used for?
FTP can be used to download public domain software, source
code, data files, research tools, utilities and documents for a variety of
platforms from publicly accessible file archives. The /pub directory is a standard
of file archives and is generally the directory in which to look for
transferable files.
FTP can also be used to upload and
download files between your microcomputer and your accounts on ROHAN, if your communications software offers the FTP
command. See section 11.0 What microcomputer software offers FTP? for more information.
Return to Contents
3.0 What is a file archive?
Basically, a file archive is a storehouse of information.
There are many file archives on the Internet. WUARCHIVE at Washington
University, Missouri is a computer
with a large program and file archive. It includes mirrors of many other
programming archives, with megabytes of stuff for DOS, Windows, Macintosh, and
other popular computer systems. It also contains the largest collection of GIF
and JPEG pictures on the Internet.
Because file archives provide the
username anonymous for FTP retrieval of files from their system, they
are referred to as Anonymous FTP sites. Their login is called Anonymous FTP
login. Your Email address is the accepted password convention for this type of
login. Anonymous FTP login works only for file transfers from a remote computer
to your local computer. It is not an account that can be accessed for general
use or used to send files to a remote computer. Finally, not every file can be FTP'd. Only files that have a protection permitting
transfer (i.e., allowing public read access) can be FTP'd
anonymously.
Return to Contents
4.0 How does FTP connect to an Anonymous FTP site?
Each computer on the Internet has a unique Domain Name (host.domain.top-domain) and a corresponding IP Address (xxx.xxx.xxx.xxx with each xxx ranging from 0 to 255)
associated with it as a means of identification. The ROHAN identification is
rohan.sdsu.edu or 130.191.3.100. This address scheme tells network programs the
location of a computer and on which network it resides. FTP uses either the
remote computer's Domain Name or its corresponding IP Address to make a
connection.
4.1 Finding a Domain Name or IP Address
There are a wide variety of books
covering Internet issues including Domain Names and IP Addresses that can be
obtained at most bookstores. New books are published each month and all can
assist you with your explorations. Also see handout #0303 Internet Resources
(available in BA-110, LL-200, at Malcolm A. Love Library, and on the web at URL
-- http://rohan.sdsu.edu/0300series.html) for further sources.
Quite often the SDSU name server program
may not be able to map a Domain Name (hupcap.clemson.edu) to its IP Address
(130.127.28.32), but you can use either. If the SDSU name server program does
not recognize the Domain Name and you don't know the corresponding IP Address,
you can use a lookup program prior to executing FTP from ROHAN and obtain that
information.
An example of host on ROHAN using two Internet
sites, hubcap.clemson.edu and arthur.cs.purdue.edu, follows. The
programs will look up either a Domain Name or an IP address on a single line
command string or via the program > prompt for multiple inquiries.
On ROHAN:
rohan% host 130.127.28.32
32.28.127.130 IN-ADDR.ARPA domain name pointer hubcap.clemson.edu
rohan% host arthur.cs.purdue.edu
arthur.cs.purdue.edu has address 128.10.2.1
arthur.cs.purdue.edu mail is handled (pri=1) by
arthur.cs.purdue.edu
rohan%
Return to Contents
5.0 Where are Anonymous FTP sites located?
At SDSU, there is a FTP archive
located on rohan.sdsu.edu with doc, ibm, mac, and html
directories and more under the /pub directory. To reach the WUARCHIVE mentioned
earlier, you would FTP to wuarchive.wustl.edu. Many FTP sites can be
accessed using the World Wide Web (WWW). Type in ftp
and the address of the site. Login as ftp and use your complete
Email address as the password. Files can be easily downloaded by clicking on
the highlighted text. For further information on Anonymous FTP sites, refer to
the handout #0303 Internet
Resources (available in BA-110, LL-200 and on the web at URL -- http://rohan.sdsu.edu/0300series.html).
Return to Contents
6.0 How do I invoke FTP on ROHAN?
Log onto your computer account on
ROHAN and issue the ftp
command at the system prompt.
SunOS 5.8
This system is for the use of authorized users only. Individuals using this
computer system without authority, or in violation of state or federal laws
are subject to having their activities monitored by law enforcement officials.
login: <-- log onto ROHAN with your
password: username and password
rohan%ftp <---- invoke FTP
Once
in the FTP program, you open a session with the remote computer of your choice,
login as anonymous and then issue a file command.
open domainname
Opens an FTP session on another host computer. In order to
do this, you must know the computer's Domain Name or IP Address. The SUN Ultra Enterprise
4000 has a Domain Name of rohan.sdsu.edu,
however rohan will suffice
if you are using FTP from another computer on-campus. This is because the sdsu.edu
part of the name refers to SDSU's domain, which
on-campus computers assume as the default. When a Domain Name is used, your
local computer obtains the IP Address from a Domain Name server. The IP Address
should be used if the Domain Name does not succeed. Example: ROHAN has an IP
Address of 130.191.3.100.
username
Prompts you to enter your account/username for the host computer.
With Anonymous FTP, you would enter the appropriate public account/username,
generally anonymous or ftp.
password
Prompts you to enter the password for the account/username entered.
With Anonymous FTP, you would enter the appropriate password, generally your
complete Email address.
get myfile
At
this point, you are ready to issue an FTP file command. In this example, you
are using the get command to copy a file named myfile
from the remote host computer.
quit
Closes
the session with the remote host computer and exits FTP.
Return
to Contents
7.0
How do I open a new FTP session?
To
log into another site, first close the current FTP session by issuing the close command. Then use the open command followed by the Domain
Name or IP Address for the new remote computer. Following opens another FTP
session run from ROHAN to 152.163.200.5:
ftp> close
221 Goodbye.
ftp> open rohan.sdsu.edu
Connected to rohan.sdsu.edu
220 rohan.sdsu.edu FTP server (Version wu-2.6.0(7) Thu Jun 29 15:28:49 PDT 2000) ready.
Name (rohan.sdsu.edu:johndoe): anonymous
331 Guest login ok, send your email address as password.
Password: jdoe@rohan.sdsu.edu <-Your Email address
230- Welcome to the San Diego State University anonymous ftp archive.
230 Guest login ok, access restrictions apply.
ftp>
Return
to Contents
8.0
What is Binary vs. ASCII?
Files
found at Anonymous FTP sites can either be stored in ASCII mode (pure text
files usually ending with either .txt or .asc) or
non-text files stored in binary mode (also known as image mode [pictures,
software, music, speech, word, etc.]). ASCII mode automatically adjusts the
file during the transfer so that the file is a valid text file when it is
stored on the receiving end. A binary file is left alone and transferred
verbatim. Before downloading be sure to set the transfer mode to the proper
type by typing or selecting ascii or binary prior to the get or mget command (See section 12.0 What FTP commands are
available?). The FTP site should respond with type set to A or type set
to I acknowledging your request.
If
you accidentally transfer a binary file with the transfer mode set to ASCII,
the file received will be corrupted and useless. However, the reverse will work
fine. If you don't know the type of a file, set the transfer mode to binary.
Then you're sure that your files will always transfer correctly.
In
the following example, we will get the binary zip file ttermp23.zip (Terra Term
Telnet Program) from an anonymous FTP session to rohan.sdsu.edu.
ftp> binary
200 Type set to I.
ftp> cd /pub/ibm
250-Please read the file README
250- it was last modified on Fri Aug 15 10:59:50 1997 - 1112 days ago
250 CWD command successful.
ftp> get ttermp23.zip
200 PORT command successful.
150 Opening BINARY mode data connection for ttermp23.zip (943376 bytes).
226 Transfer complete.
local: ttermp23.zip remote: ttermp23.zip
943376 bytes received in 0.072 seconds (12744.91 Kbytes/s)
ftp> quit
rohan%
The
files are now in your account. This file is in a compressed format, so it will
have to be uncompressed before it can be used.
Return
to Contents
9.0
What are compressed files?
Many
files at Anonymous FTP sites are compressed so they occupy less space on their computers
and facilitate faster transfer across the Internet. Compressed files have file
extensions like .z, .gzip, .bin, .hqx,
or .zip.
Such
files must be locally decompressed. The decompressing program used depends on
the type of data compression initially employed. For instance, files which end
with .z can be uncompressed or extracted using the UNIX utilities uncompress,
while files ending with .zip can be uncompressed using the WIN
program WinZip. Below are operating systems and compressed file types with
their associated programs.
|
Operating System
|
File Type
|
To Uncompress a
File
|
To Compress a
File
|
|
WIN
|
.zip
|
WinZip
|
WinZip
|
|
MAC
|
.bin, .hqx, .sit, .cpt, .sea, .seq, .pit, .dd, plus DOS (.zip, .lzh, and .arc),
and UNIX (.z and .tar files)
|
Stuffit Expander
|
Stuffit Expander
|
|
UNIX
|
.gz
|
gunzip
|
gzip
|
|
UNIX
|
.z
|
uncompress
|
compress
|
A
copy of the file compression program, pkzip (pkzip204.exe),
can be downloaded for DOS/WIN PC users via Anonymous FTP to rohan.sdsu.edu
from the /pub/ibm directory.
For MAC users, a copy of Stuffit Expander (the file
compression program) can be obtained using Anonymous FTP to wwwhost.ots.utexas.edu
from the /pub/mac/compression/ directory. (The file
name is stuffit-expander-401.hqx)
Return
to Contents
10.0
What are tar files?
Sometimes
the need to compress involves a group of files and becomes a two stage process.
When it is necessary to bundle a group of files together for transfer, the UNIX
program tar is used. tar can bundle programs (many
related files) with their electronic manuals and maintain their directory and
sub-directory configurations. Since it can bundle and unbundle
but not compress, a compression program is used for the second stage. To alert
users of its use, tar files traditionally have tar somewhere in their filename.
If the tar file has been through both stages of the process, the filename might
end in .tar.z (a compressed tar file).
To
display the contents of a tarred file a screen at a time, enter:
tar tvf filename | more
where your file's name is substituted for filename in the above example
command.
To
untar a tarred file, type:
tar xvf filename
where your file's name is substituted for filename in the above example
command.
Return
to Contents
11.0
What microcomputer software offers FTP?
There
are many software programs using TCP/IP protocols that can be used with an
Internet connection. Following are some samples of software programs that offer
FTP capabilities:
|
FTP Software
Programs
|
|
WIN versions
|
MAC versions
|
|
WS_FTP (freeware for Windows 95)
|
Fetch (public domain pkg.) (Available from TNS)
|
When
using one of the above software packages, refer to their documentation for a description
of their installation and use. Also see handout #0303 Internet Resources
(available in BA-110, LL-200, at Malcolm A. Love Library, and on the web at URL
-- http://rohan.sdsu.edu/0300series.html) for additional information.
Return
to Contents
12.0
What FTP commands are available?
Most
commands used by the FTP program are similar to UNIX commands and most FTP
sites are on UNIX-based computers. Typing ? at the FTP> prompt will produce a list of FTP commands.
FTP> ?
Commands
may be abbreviated. Commands are:
! cr macdef proxy send
$ delete mdelete sendport status
account debug mdir put struct
append dir mget pwd sunique
ascii disconnect mkdir quit tenex
bell form mls quote trace
binary get mode recv type
bye glob mput remotehelp user
case hash nmap rename verbose
cd help ntrans reset ?
cdup lcd open rmdir
close ls prompt runique
Typing
help command where command is replaced by one from
the list will display a one line description of the command typed with usage
requirements.
FTP> help remotehelp
remotehelp - get help from remote
server
FTP> help reset
reset - clear queued command replies
Here
are some FTP commands that will be helpful for almost all operating system
environments.
ascii
Configures FTP to receive ASCII files (usually the default).
binary
Configures
FTP to receive binary files (both test and binary files can be transferred in
binary mode, so switching to this mode as soon as you start FTP won't hurt
anything).
cd
Changes
to a directory (depends on computer file structure).
cdup or cd ..
Changes directory up one level.
close
Closes an FTP session without quitting FTP.
delete
Deletes
a file on the remote computer (needs the name of the file to follow command).
dir
Produces
a more detailed listing of files on the remote computer where file names begin
with a dash and directory names begin with the letter d.
exit
Closes
an FTP session and quits FTP.
ftp
Starts
an FTP session (see open command).
get
Copies
(gets) a file from the remote to the local computer (needs the name of the file
to follow command).
help
Provides
a help listing; used with a command, it provides help on that command.
lcd
Changes local directory (send data to floppy drive).
ls
Produces a brief listing of files on the remote computer.
mdelete, mls, mput, & mget
Same
as the delete, ls, put, and get commands except the
"m" put in front of the commands allows an action on multiple files.
For example: mget file1 file2
would get both file1 and file2 with one command. Entering mget
would prompt you for the files. Wildcards can also be used. mput is generally not used during Anonymous FTP
sessions.
mkdir
Creates
a directory (depends on computer file structure)
open
Opens a session with a remote computer (needs the Domain Name or IP
Address of the remote computer to follow command).
put
Copies
(puts) a file from the local computer onto the remote computer (needs the name
of the file to follow the command). Generally not used during Anonymous FTP
sessions.
pwd
Displays
the complete path of your present working directory on the remote computer
(depends on computer file structure).
quit
Ends an FTP session.
rename
Renames
a file on the remote computer (you are prompted for the new filename).
rmdir
Deletes
a directory (depends on computer file structure).
user
Issues a user command (used for re-logging on to a remote computer
in case initial logon fails).
For
more detailed information, use the help function on your FTP program.