Using FTP

What is FTP?

1. First, the general notion of copying files back and forth over a network, but without using a file server.
2. The File Transport Protocol or FTP, a network protocol for copying files over a network.
3. And, finally, the actual command line oriented FTP program itself, as found in UNIX or Windows.

Copying Files over the Internet

You could also use one of the secure/SSH based versions like SCP (Secure Copy Program) or SFTP (Secure FTP), or their graphic front ends. These all use encryption for the login process (when you enter your username and password on the server) as well as for the data transfer to keep your information private. You should prefer to use a secure version of FTP if you can; we are going to refer to both secure and unsecure versions as just FTP.

FTP requires an Internet network connection. In order to use FTP from home, you must have an ISP (for DSL or cable modem), or use the PPP (Point to Point Protocol) software with a dial up service provider (like campus Network Operations or AOL, Earthlink, etc).

You can use an Internet browser like Internet Explorer or Netscape Navigator to download files from an anonymous FTP server on the Internet to your computer using FTP. Just use the ftp:// URL scheme along with the address of the FTPserver as the URL. The browser will take care of logging you in as user "anonymous". For instance, in the figure at the right, we have accessed files on ntserve.ucsd.edu using the URL: ftp://ntserve.ucsd.edu (using the Macintosh version of Internet Explorer ).

However, to upload files (like your homework) from your home computer to the class server, you must have an FTP program. (You will also need to have an account on the computer you wish to upload to.) Not only will FTP let you turn in your homework from home, but you can also upload (or download) large files (like software programs) that are too big to fit on a floppy disk.

It's also worth mentioning that while you can send files back and forth via email, many mail servers have limits on the size of a single message. If the data you are sending is binary in nature (like an image, or word processing document), it has to be encoded as ASCII in order to pass through the mail system. This encoding will make the document even larger than it is in its binary format! FTP does not have this size restriction.

This is not the transparent operation that one has using file server disks, such as Appleshare or a network drive, where the remote computer's disk is mounted on your computer, and appears (and acts) just like a local hard disk. On a Macintosh, the file server's disk icon appears on the desktop, while in Windows, the icon appears in "My Computer" (icon usually found on the upper left hand of the desktop; or in the Start menu of Windows XP). With a file server, you are able to double click on the file server icon to open and browse it's contents. You can open (double click) and modify the original copy of a document on the file server. Or using the SaveAs dialog, you are able to navigate directly to the file server disk and save there.

With FTP on the other hand, you must

1. First copy (FTP) the file from the remote computer to your local hard disk
2. Then make your modifications, save them
3. And finally copy (FTP) the new version back either as a new document with a new name, or on top of (replacing) the original.

The Network Protocol

FTP is a client/server protocol. In order to access files on a computer via FTP, that computer must be running an FTP server.

The FTP Program

Despite its somewhat crufty command line user interface , there are many implementations of FTP, both the client (user oriented) side and the server side. This is one of the main advantages of FTP over the different types of file servers, there are many versions of FTP for a variety of software and hardware configurations. I.e., it is possible to FTP files to/from a server running one type of software (e.g., a Linux server like icogsci1) to a client like Macintosh.

Using the FTP Program

	ftp icogsci1.ucsd.edu

In Windows, you can use the Run command in the Start menu (Start->Run), or open a MSDOS window (in the Programs Menu--in Windows 2000 and XP it is called: Start->(All)Programs->Accessories->Command Prompt), and then type FTP and the host name you want to connect to (like above).

You can also simply type: ftp. Then use the open command within FTP to specify the remote connection. E.g., open icogsci1.ucsd.edu

On a Macintosh with NCSA Telnet, you use the File->Open dialog to specify the host name, and then click the "Ftp Session" box; this will create an out going FTP connection to the host. Note that both NCSA Telnet and Better Telnet allow you to do a somewhat peculiar thing, namely to FTP into your Macintosh. In this scenario, you use Telnet to log into the host (e.g., icogsci1), and then FTP back to your Macintosh. (You may have to set the preferences for the Telnet software to allow for incoming connections). Now the "remote" computer is your Macintosh, and the "local" computer is the host you telnet-ed to.

Local vs Remote

Another thing that makes FTP hard is that there are two computers involved. When you use a file server, there are also 2 computers involved, but you are not really aware of the file server as a computer, since it appears to be a local disk. With FTP, on the other hand, you need to be aware of the both computers: the local one, which has the screen and keyboard you are using. And the remote computer, which is the one you want to upload to, or download from--the one you "FTP to".

Logging In

Anonymous FTP Servers

For transferring files to or from your class accounts, you will, of course, log in with the appropriate class account and corresponding password.

Some FTP servers, for instance the one built into NCSA Telnet for the Macintosh, do not automatically prompt for the user (account) name after the connection is made. You will have to use the user command within FTP to start the process.

If you make a mistake logging in, say, by mistyping your password, you can restart the log in process by using the user command.

The 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
ftp>

Typically, you only use a very small subset of these, for instance, for navigation.

Navigating the Remote File System

lcd

Navigating through your folders on your PC with lcd can be difficult:

• Changing directory to a different drive letter can be tricky, depending on exactly which version of FTP you are using on the PC. It might be: lcd a: for instance, or it might be as simple as a: like you would type at a DOS prompt. Or, maybe you have to select both the drive and a folder, like lcd a:\ or lcd c:\temp
• File and folder names with spaces in them are a major pain. . Use quotes (") around the name with the space in it. E.g., lcd c:\"My Documents"
• Some FTPs will use 8 characters for the file name, and truncate the rest! (This is a throw-back to the 8.3 file names used in DOS.) Thus, instead of lcd "Program Files", you probably have to do: lcd program~1.

It might be easier to use the "Command Prompt" window to navigate to the folder where you will get your data to or put your data from. And then start FTP afterwards. That way, you shouldn't need to lcd.

By the way, if you start FTP via Start->Run in one of the ACS Windows XP labs, it appears as if the initial local directory is your My Documents folder.

Copying Files -- get

There are put and get synonyms for send and recv, respectively.

For example:

	get foo

You can also rename the file during the copy process.

	get foo bar

put

	cd public_html
	put index.html

Multiple Files

For instance,

	mget *.html

By default, mget and mput will ask you about each file name before doing the actual copy/transfer. You may find it convenient to use the prompt command before starting the mput or mget to turn off prompting during the copy process. The prompt command is a toggle; use the command once to turn off prompting, use it again to turn prompting back on; like flipping a light switch.

Directory/Folder Hierarchies

For large directory structures, it may make sense to "bundle up" the folders and files before FTP-ing, perhaps using the zip program. Then FTP the single bundle and then undo (unzip) it after the copy. UNIX users often use the tar command to create such a bundle, and then use tar again at the remote end to undbundle.

The secure version of FTP called: SCP, usually takes a -r recursive flag argument. The -r copies a directory hierarchy!

Binary or ASCII

Some forms of FTP client software (for instance, on the Macintosh and under DOS or Windows) do special processing of the end of line character in text files.

That is, the end of line character for text is a line feed (0xa in hexadecimal) on UNIX systems, but a carriage return (0xd in hex) on the Macintosh. Windows or DOS programs want both a carriage return and line feed at the end of each line. In ASCII mode, FTP will translate the end of line convention on the sending system to that required on the receiving end.

All other files should be transfered in binary mode. If you don't know what sort of file you have, use binary mode. All 8 bits are transfered in binary more. There is no translation of any sort. There is an FTP "binary" command to change to binary mode (just bin will do).

In particular, all graphic images, program files, tar archives, zip files, and even word processing documents (.doc) should be transfered in binary mode. Copying such a file/document in ASCII mode will corrupt it (badly), so that it can't be used.

An Example

• The first thing to do is locate what folder MONKEY.GIF actually resides in. You can use Start->Find->"Files or Folders". Remember that if you need to, you can stretch the "In Folder" part of the "Find" dialog in order to see the full pathname for the file.
• Once you have the whole pathname, start up a command line window by Start->Programs->Accessories->Command Prompt (or Start->Programs->Dos Prompt).
• Use the cd command to change to the folder you found MONKEY.GIF in. Say that folder was: C:\Programs\Netscape\Downloads. You would type:

  	cd c:\programs\netscape\downloads
  

  Note, should part of the folder name contain a space, use quotes (") around the whole folder name. For example, your "My Documents" folder has a space:

  	cd "My Documents"
  

• Create a network connection for your computer using the procedure you normally use to get on the Internet, perhaps by using "Dialup Networking".
• Now start up FTP to the class server:

  	c:\programs\netscape\downloads ftp icogsci1.ucsd.edu
  

• You will be prompted for your user name and password, type in your class account name (cg3xzz) and password.
• Now you should have an "ftp> " prompt.
• Make sure that FTP will be doing binary transfers unless you are sure that you want an Ascii transfer.

  	ftp> binary
  

• You can use the dir command to give you an ls -l type listing of your home directory. And you can use the cd to navigate to subfolders, if you need to. Suppose the MONKEY.GIF file needs ultimately to be in your public_html folder on the class server.

  	ftp> cd public_html
  

• Now put your file on the server. This may take a few moments depending on the size of your file and the speed of your Internet connection.

  	ftp> put MONKEY.GIF
  

  Or copy, and rename it at the same time by providing a new file name to as the second argument to the put command.

  	ftp> put MONKEY.GIF monkey.gif
  

• You can use dir to verify the file got there, then quit.

  	ftp> dir
  	ftp> quit
  

A GUI Front End

Once you have logged into the remote computer, you are presented with a somewhat graphical view of the files in the current directory (on the remote computer); something like view that Windows Explorer (not Internet Explorer).

Copying a file can be as easy as double clicking on it.

Fetch

Here is the Fetch open (log in) dialog.

And here is the display of the remote file system.

Fetch and Macintosh Special Note

• In order to copy a Macintosh file from one Mac to another using FTP, you have to use a special format called Macbinary ||.
• To copy/FTP a file from a Macintosh to a UNIX or Windows system, you probably want to avoid doing a "Macintosh" copy.

Fetch tries to figure out the format to put files in. Sometimes this automatic determination is incorrect, so you should plan to override it manually. Part of the put dialog allows the user to specify the exact format. For images and sounds, "raw binary" is the right choice, probably for Word (or other word processing documents) too.

WS-FTP

Here is the initial, "log on" window.

And here is the display once you have logged into the remote system.

The WS-FTP dialog is similar to Fetch's except there are 2 sets of files listed. The files and folders on the left are on the local disk; those on the right are on the remote system.

Generally, the names of all the folders are displayed before the file names, however, you can alter that behavior (select the Options button). As in UNIX, .. is a shortcut for the parent/upper folder. Click on the .. entry to move up one folder level, just like in the Windows Save and Open dialogs.

As usual with Windows, you need to be careful about the 8.3 type filenames.

To copy a file, from the system and folder on the left (the local system) to the folder on the right, simply select the file (or folder) in the left window and then click the -> button. WS_FTP will copy a whole folder hierarchy too--much more convenient than the command line FTP.

Getting WS_FTP

You can download the ws_ftple.exe installer file from the Windows_NT->ftp folder (on ntserve). Be sure to remember the folder that you specified in the SaveAs dialog.

Once it has copied down, then you can open that folder, and double click on ws_ftple to get it installed.

Or use the command line oriented FTP. First, Start->Programs->MSdos to open a dos window. Then in that window type:

• 	mkdir c:\temp
  	cd c:\temp
  

• ftp ntserve.ucsd.edu
• Login as: anonymous
• For your password, give your @ucsd email address
• At the ftp> prompt, type:

  	cd windows_nt/ftp
  	binary
  	get ws_ftple.exe
  

• There will be a pause as the program is copied, then a message about how many bytes were copied.
• Quit from FTP

  	quit
  

• Now install the program by typing:

  	ws_ftple
  

  and answering the questions

FTP Summary

• When we say "FTP your file", we mean copy it over the network using an FTP type program.
• FTP stands for File Transfer Protocol
• FTP is not as convenient to use as a file server. You have to copy the file(s) to the local machine before you can work on them, and then copy them back. But you can accomplish the same tasks.
• FTP is not convenient for copying a folder or directory hierarchy. (You can copy multiple files at a time, but not the contents of folders).
• The most frequently used commands are:
  • get (from remote computer to local one)
  • put (from the local hard disk onto the remote computer)
  • binary (set the transfer mode to binary for images, word processing documents--everything but text files)
• Use cd to change folders on the remote system
• Use lcd to change folders on the local system
• Use quotes (") around files or folder names with spaces in them; e.g., lcd c:\"my documents"
• You can copy files to or from your friends account (with their permission, of course ).
  • Log in to your account
  • ftp to your friend's computer (it can be the same as yours!)
  • have your friend log in as herself (at the ftp username:> prompt)
  • get or put files! The "local" files are your account, the "remote" files are your friend's.
• Fetch and WS-FTP are graphical versions of FTP
• you might need to be careful of 8.3 filename limitations if you are using Windows and/or WS-FTP
• If you are using a Macintosh, then use Macbinary mode to transfer objects which should wind up as Macintosh objects (documents, applications). Be sure not to use Macbinary to transfer things that will wind up not being Macintosh objects; e.g., graphic images.
• You can use FTP to copy files that are larger than a floppy.
• You can use the ftp:// as the scheme in a URL to download files from within a browser.

Terms to Know

©opyright 1995-2004 Mark R. Wallen Last updated: Sun Sep 19 12:20:41 2004