Linux Unleashed, Third Edition:Types of Linux





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FTP Sites
The File Transfer Protocol (FTP) is a widely used Internet protocol (part of the TCP/IP family) that lets you transfer files from remote machines. There are several anonymous FTP sites that distribute Linux software (anonymous means you don’t need an account on the remote machine to access the files; you log in as “guest” or “anonymous” and use your name or email address as a password). If you have access to the Internet, either directly or through an online service provider like CompuServe or America Online, you can access these Linux distribution sites.

To use FTP, you must be on a machine that supports TCP/IP. This can be your existing PC running a DOS or Windows package or a UNIX or Linux workstation, either of which is connected to an Internet service that gives you FTP capabilities. Both ends of an FTP connection must be running a program that provides FTP services, although it’s a safe bet that if the system you are dialing into is an FTP site, they are running FTP! To download a file from a remote system, you must start your FTP software and instruct it to connect to the FTP software running on the remote machine.
The Internet has many FTP archive sites. These are machines designed to allow anyone to connect to them and download software. In many cases, FTP archive sites mirror each other so that they have exactly the same software. You connect to the site that is easiest to get to or gives you the best response speed. The most commonly used FTP site for Linux software is sunsite.unc.edu. The archives at sunsite contain a comprehensive list of available Linux software and older kernels, drivers, and utilities. Many of the CD-ROM collections you can buy in a store are simply copies of the contents of sunsite. If you’re looking for Linux through FTP, sunsite.unc.edu is one of the best places to start.
Using FTP to Connect and Download Files
Using FTP to connect to a Linux FTP site is quite easy (assuming you have access to the Internet, of course). You can start FTP with the name of the remote system you want to connect to or enter it after starting FTP (the former is easier). If you are directly connected to the Internet, enter the ftp command with the name of the remote site, such as:



ftp sunsite.unc.edu


In this case, we’re using a command-line interface, although there are some very useful GUI-based FTP clients, such as those with Windows X client packages. Using this type of interface is a lot friendlier than command-line FTP because it mirrors the Windows Explorer interface. You simply select the files you want on the remote machine and drag them to a folder on your machine. Packages like eXceed can be used to access your Linux X server from other machines on a local area network.

If you are using an online service such as CompuServe or Delphi, usually you must access their Internet service area and invoke FTP from there. Most online services let you enter the name of the FTP site at a prompt. A few services place limitations on the amount of traffic you can transfer, so downloading Linux may be bothersome with these services unless you like being hit with high surcharges.
Since many people use command-line-based FTP to obtain their Linux software, that’s the version we’ll use in this section. You can start FTP after you have connected to the Internet through your ISP. If you are using a Windows machine, a DOS window is often the easiest way to connect. Open a DOS window and enter the name of the server you want to reach on the ftp command line.
Once you issue the FTP command, your system attempts to connect to the remote machine. When it completes the connection successfully, the remote machine prompts you for a user ID. You must have a valid user ID and password for that system unless it supports anonymous FTP (which all Linux FTP sites do). When you first connect and before you log in, a message usually displays informing you that anonymous FTP is supported on the remote system. For example, the login below for the Linux FTP archive site sunsite.unc.edu immediately tells you anonymous login is acceptable:


ftp sunsite.unc.edu
331 Guest login ok, send your complete e-mail address as password.
Enter username (default: anonymous): anonymous
Enter password [[e-mail]]:
|FTP| Open
230- WELCOME to UNC and SUN’s anonymous ftp server
230- University of North Carolina
230- Office FOR Information Technology
230- SunSITE.unc.edu
230 Guest login ok, access restrictions apply.
FTP>


The login for an anonymous FTP site is usually “guest” or “anonymous.” The login message usually tells you which is used or you can try both. The remote machine will prompt you for a password in most cases. You don’t have to supply one with some systems, while others ask for your username or email address. This is used for tracking purposes only and has no security problems associated with it (unless you don’t have a password on your local account!).

After the login process is finished and you have supplied the login and password, you then see the prompt “FTP>.” This indicates the system is ready to accept FTP commands. Some systems display a short message when you log in which contains instructions for downloading files as well as any restrictions that are placed on you as an anonymous FTP user. Other information may be displayed about the location of useful files. For example, you may see messages like this one from the FTP site sunsite.unc.edu:


To get a binary file, type: BINARY and then: GET “File.Name” newfilename
To get a text file, type: ASCII and then: GET “File.Name” newfilename
Names MUST match upper, lower case exactly. Use the “quotes” as shown.
To get a directory, type: DIR. To change directory, type: CD “Dir.Name”
To read a short text file, type: GET “File.Name” TT
For more, type HELP or see FAQ in gopher.
To quit, type EXIT or Control-Z.

230- If you email to [e-mail] you will be sent help
information
230- about how to use the different services sunsite provides.
230- We use the Wuarchive experimental ftpd. if you “get”
<directory>.tar.Z
230- or <file>.Z it will compress and/or tar it on the fly. Using “.gz”
åinstead
230- of “.Z” will use the GNU zip (/pub/gnu/gzip*) instead, a superior
230- compression method.






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