In addition to these domain names, there are many two-letter country codes, e.g.
.ca : Canada
.jp : j.a.pan
.uk : United Kingdom
.us : United States
and many more.
To send electronic mail to someone over the Internet, all you need to know is their "username", or "handle". This is followed by an at-sign, the node name, and any domain names. Thus
[email protected]
donotes a private citizen in Chicago, Illinois, in the U.S. Joe"s computer is called "locoweed".
As another (real) example,
[email protected]
is the E-mail address of the U.S. President.
In the examples that follow we will give details for a typical character-oriented computer. Windowing systems with menus, dialog boxes, and so on will hide many of these details, but they are happening behind the scenes. Also, once you are connected, you may be faced with an old-fashioned command-line system.
Electronic Mail (E-mail) The details of using the mail system depend on your system, but basically it looks like this:
% mail Welcome to Mail, Version 99.3 ...
mail> send
To: [email protected] Cc: [email protected] Subj: I"m on Internet Type your message. Control-Z to exit
Bill--
I just got my Internet connection today. My address is [email protected]
Give my best to Al,
PDQ
% Telnet In addition to using an Internet address to send E-mail, you can use it to call a computer. This is rather like dialing up a computer with a modem, except that the local computer (the one you called with *your*
modem) is calling up the remote computer:
your PC or Mac --> "local computer" --> "remote computer"
The example a.s.sumes that "home>" is the sh.e.l.l prompt given by your local computer and that "%" is the prompt given by the remote computer (see Section 2.2 on "sh.e.l.l prompts"). So remember, you don"t type them.
home> telnet hoople.usnd.edu Welcome to node HOOPLE. Now running Opus 2.0
username: pdq pa.s.sword: Last login 23:14:55 15-JUN-1752 You have mail.
% % logoff Session with hoople.usnd.gov terminated at 21:19.
home> This method of connecting to another computer is called "telnetting".
In effect, you have used the local computer to telephone the remote computer. You can now do anything on the remote computer (with certain restrictions) you could do if you were "actually" logged on.
SPECIAL PROBLEMS WITH TELNETTING
Sometimes telnetting will put you into a menu-type program or even a "screen oriented" program. A special problem here is getting the other computer to recognize what type of screen you have. Since most communications software "emulates a terminal", this amounts to telling the other system what type of terminal your communications system is emulating.
E.g., on a UNIX system you might type:
% set term vt100
to tell the other system that your communications software thinks it is a VT100 terminal (a very common choice for emulation programs).
If you don"t get this exactly right, your telnet session will "sort of work". It"s probably not worth spending a lot of time on this problem for a brief contact with the other computer. If you are going to work on the remote computer every day, however, you will want to get it right. Most "flaky" behavior can be traced to this problem.
File Transfer Protocol (FTP) It is easy to transfer files over the Internet using a special protocol called FTP. FTP takes the place of programs like XModem or Kermit that may be familiar to you if you use a bulletin board service. Now, you might ask, if FTP transfers a file, what is the differnce between sending E-mail and FTP; why prefer one over the other?