Open command prompt terminal window and type the ftp prompt

4.1 Services

Your computer, the local computer uses programs called clients to interpret the information that you receive. The other computers, the remote computers, use programs called servers to provide this information to your computer.

4.1.1 HTTP and The Web

On your local computer, you use a client program called a web browser. Contrary to what you might have been lead to believe, there are actually a number of web browsers available for both Windows and Linux. These include Microsoft's Internet Explorer, Netscape Navigator, and the Mozilla Firefox browsers.

You can also create your own web page. The easiest way to do this is to use one of the common word processors, such as OpenOffice, Microsoft Word, or WordPerfect. These programs will allow you to produce simple web pages, combining text, hypertext and images.

But these pages aren't flashy. Flashy means frames and scripts and animations. It also means spending lots of money on a fancy web page design program. These programs allow you to create many interesting effects on your web page, but they are more complex to use than the word processors that you are probably already familiar with.

Once you have the pages designed, you'll need a computer to put them on, so that other people can view them. This is called web hosting.

The second most visible aspect of the Internet is probably e-mail. On your computer, you use an e-mail client, which connects to a mail server. When you set up your e-mail account, you are given a unique name in the form of user@domain. You are also asked to provide a password to use to retrieve your e-mail.

The SMTP protocol, which is used to send e-mail, does not require a password. This may not have been a fault when the protocol was designed, and the Internet was a small world inhabited by like minded people, but now it has become a loophole which allows for unauthorized use of mail servers and various other tricks, such as 'e-mail spoofing', in which someone sends an e-mail that appears to come from another address. However, some mail servers minimize this flaw by implementing an authentication step, in which you must prove your identity before you can send an e-mail.

the right knowledge and tools can relatively easily 'sniff out' your password. (For ideas on making your e-mail more secure, see Lesson 9: E-mail Security.)

4.1.3 IRC

Find and join three IRC channels which focus on security topics. How do you join in the public conversation? What do you have to do to have a private conversation with a person?

It is possible to exchange files through IRC. How could you do this? Would you always want to exchange files through IRC? Why or why not?

Exercises:

Both Windows and Linux come with a basic, command line ftp client; to access it, open a command prompt or terminal window and type:

! delete literal prompt send

? debug ls put status

bell get mget quote user binary glob mkdir recv verbose bye hash mls remotehelp
cd help mput rename
close lcd open rmdir
Some important commands are:
ftp> open <domain.name>
Which connects you to the ftp server named domain.name.

ftp> close
Which disconnects you from the remote ftp server.

ftp> quit
Which shuts down your local ftp client.

331 Anonymous login ok, send your complete email address as your password.

9

230-

Welcome to ftp.anon.server, the public ftp server of anon.server. We

230 Anonymous access granted, restrictions apply.

From here, you can use the ls, dir, cd and get commands to download files from the remote server to your local computer.

To access a telnet server, you will need to have an account and password set up for you by the administrator of the server, because the telnet program allows you to perform a large number of actions, some of which could severely compromise the remote computer.

Telnet was used in the past to allow computer administrators to remotely control servers and to provide user support from a distance.