1. Application of the Internet 1998/12/09 KEIO University, JAPAN Mikiyo Nishida/west@sfc.wide.ad.jp

2. Overview of this section E-mail World Wide Web (WWW) Connecting by telephone line Other Common Application Application for administrative use Application for security

3. E-mail The most using application in the Internet E-mail service is constructed 2 parts. –Mail messages transferring over the network –User getting own mails

4. E-mail / SMTP SMTP - Simple Mail Transfer Protocol –This protocol provides mail transferring procedure between hosts/servers –SMTP is very simple protocol (Simply, delivering mails)

5. E-mail / sendmail “sendmail” is mail delivering deamon –“sendmail” is working on Mail Server –Each mail server’s “sendmail” deamon transferring mails

6. E-mail / POP POP - Post Office Protocol –This protocol provides the user downloading mails from mail server –Currently using POP3 (POP version3)

7. World Wide Web (WWW) The most famous Internet Application Killer Application –Mostly the Internet traffic is occupied by WWW

8. WWW / HTTP HTTP - Hyper Text Transfer Protocol –This protocol provides the way of WWW contents transferring –HTTP is simple protocol send “GET (URL)” and reply contents HTTP service providing daemon called “httpd”

9. WWW / URL URL - Uniform Resource Locator –URL is the description of resource type (using protocol), place –example: http://www.wide.ad.jp/index.html ftp://www.sfc.wide.ad.jp/~west/hoge.zip

10. WWW / HTML HTML - HyperText Mark-up Language –HyperText is the text including logical structure (link, picture, character size, etc) –HyperText can include related link information –Web Browser is browsing HTML contents

11. WWW / Browser Browsing HTML text –Formatting and displaying html text –Following link in html text –Integrating some Internet Service –Famous browsers: Netscape Navigator, Microsoft Internet Exploler

12. WWW / Java Java is one of programming language (Developed by Sun Mircosystems) Java can program “Java Applet” Java Applet is runable on the WWW Browser

13. Connecting by telephone line SLIP - Serial Line IP –The protocol provides the way of transferring IP Packet on the serial (telephone line, etc) line PPP - Point to point protocol –PPP is upgrading SLIP –Dynamic IP Address Assign –CarriedmMany network information

14. Other Common Applications(1) FTP - File Transfer Protocol –Sending and receiving remote file, local file TELNET –Provides remote host’s terminal –Login to remote system (UNIX)

15. Other Common Applications(2) DNS - Domain Name System –Distributed Database system, matching IP Address and hostname –example: 203.178.143.111 <> myhost.wide.ad.jp

16. Application for network administrative use ping –checking network reachability traceroute –tracing the route to destination

17. Application for Security SSL - Secure Socket Layer –Encrypting and decrypting data at the socket SSH - Secure Shell –Encrypting remote shell –Hidden password and data by powerful encrypting method