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Go to this URL, look up, and read the definition for the word "protocol":
www.whatis.com
Go to this URL and read the definition
for the acronym "SMTP":
www.whatis.com
Look up the definitions for "POP3," "IMAP," "sendmail" and "RFC (Request for Comments)" at the same site:
www.whatis.com
This is the site where you can find all of the RFCs archived:
www.rfc-editor.org/
Skim through RFC 821 at this site:
ftp://ftp.isi.edu/in-notes/rfc821.txt
Note also that the standard format for email messages is defined in RFC 822:
ftp://ftp.isi.edu/in-notes/rfc822.txt
Read the "SMTP with telnet" tutorial at this URL:
www.daemonnews.org/199905/telnet.html
Follow the directions in the tutorial to send yourself an email message. Use smtp.ucsc.edu as your mail server.
Look up the definition of HTTP:
www.whatis.com
Skim through RFC 2068 which defines HTTP 1.1. Read especially section 9: Method Definitions:
www.ics.uci.edu/pub/ietf/http/rfc2068.txt
Try fetching the front page of Yahoo using telnet with the following sequence of commands:
telnet www.yahoo.com 80
get / http/1.1
Compare this telnet session with the one you performed to send email. Note, for instance, that the email server usually listens to port 25, while web servers usually sit on port 80.
Look up the definitions of "port" and "port number":
www.whatis.com
Read the definition of NNTP:
www.whatis.com
Skim through RFC 977 which defines the Network News Transfer Protocol:
ftp://ftp.isi.edu/in-notes/rfc977.txt
Read especially section 3: Command and Response Details
Try fetching an article or two with the following sequence of commands:
telnet news.ucsc.edu 119
group alt.tv.x-files
article 721365
quit
Note that the article number I used above (721365) won't necessarily work when you try this example out. Read the subsection of the RFC that describes the ARTICLE command to understand what the number following the command represents. You will find that the GROUP command will give you a current, valid range of article numbers that can be used with the ARTICLE command.
If you want to learn another protocol as well after trying out SMTP, HTTP, and NNTP, read about FTP:
www.whatis.com
Read RFC 354 that defines the File Transfer Protocol
ftp://ftp.isi.edu/in-notes/rfc354.txt
And, telnet to UCSC's FTP site to try it out:
telnet ucsc.edu 21
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