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Internet Services

Internet Services. Some samples: email, login, file transfer, news document distribution, web services, etc…. E-mail. TCP Port: 25 uses Simple Mail Transfer Protocol Clients: mailx, pegasus, MS-outlook, Netscape messenger Servers:

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Internet Services

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  1. Internet Services Some samples: email, login, file transfer, news document distribution, web services, etc…

  2. E-mail TCP Port: 25 uses Simple Mail Transfer Protocol Clients: mailx, pegasus, MS-outlook, Netscape messenger Servers: Sendmail (Unix), MS-Exchange (NT), Netscape Messaging Server (Unix, NT)

  3. Terminal Emulation Port: 23 (uses Telnet Protocol) Clients: telnet Servers: telnetd Port: 22 Clients: ssh Servers: sshd

  4. File Transfer Uses File Transfer Protocol Port: 21 Clients: ftp Servers: ftpd (Unix), IIS (NT and Windows)

  5. News Uses Network News Transfer Protocol Port: 119 Clients: MS-Outlook, Netscape Collabra Servers: nntpd(Unix)

  6. Electronic Documents Gopher Protocol Port: 70 Clients: wingopher Servers: IIS

  7. Web Services Uses HTML Protocols port: 80 Clients: Netscape Navigator, MS IE Servers: IIS for Windows Platform, Apache Tomcat for Java Platform

  8. With each of the preceding, multiple clients may communicate with a single server

  9. E-mail • The normal usage of this application is to create a message for another user on a local or remote computer system and have it delivered electronically. • An example of “push” delivery

  10. e.g. mail johnm@vax.ftp.com Subject: How is the Project? Message ----------------------------------------------- Hi, I got your last message.... ..... etc

  11. The message is sent from the originating mail serving application to the destination mail serving application via a route that may pass through many mail servers on its way.

  12. Mail servers Mail clients

  13. SMTP Headers Received: from (2)ALPHA8.MONASH.EDU.AU by (1)silas.monash.edu.au (8.9.3/1.1.29.3/16Feb01-1022AM) id XAA0000955685; Tue, 23 Apr 2002 23:50:56 +1000 (EST) Received: from blammo.monash.edu.au ([129.179.1.74]) by (3)vaxh.monash.edu.au (PMDF V5.2-31 #39306) with ESMTP id <01KGX6J1JA328WW4SY@vaxh.monash.edu.au> for pravin.shetty@silas.monash.edu.au; Tue, 23 Apr 2002 23:50:48 +1000 Received: from blammo (unknown [127.0.0.1]) by (4) localhost (Postfix) with ESMTP id 5425712C002 for <pravin.shetty@silas.monash.edu.au>; Tue, 23 Apr 2002 13:50:43 +0000 (/etc/localtime) Received: from mail1.monash.edu.au (bigted.monash.edu.au [129.179.11.60]) by (5) blammo.monash.edu.au (Postfix) with ESMTP id 14A8512C002 for <pravin.shetty@silas.monash.edu.au>; Tue, 23 Apr 2002 23:50:43 +1000 (EST) Received: from ALPHA1.MONASH.EDU.AU ([129.179.1.1]) by (6) mail1.monash.edu.au (Netscape Messaging Server 4.15) with ESMTP id GV0X4I00.NBA for <pravin.shetty@mail1.monash.edu>; Tue, 23 Apr 2002 23:50:42 +1000

  14. SMTP Headers Received: from (8)blammo.monash.edu.au ([129.179.1.74]) by (7)vaxc.monash.edu.au (PMDF V6.1 #39306) with ESMTP id <01KGX6IRZ3MQ922MOH@vaxc.monash.edu.au> for pravin.shetty@mail1.monash.edu (ORCPT pravin.shetty@inftech.monash.edu.au); Tue, 23 Apr 2002 23:50:31 +1000 Received: from blammo (unknown [127.0.0.1]) by localhost (Postfix) with ESMTP id 762F512C002 for <pravin.shetty@inftech.monash.edu.au>; Tue, 23 Apr 2002 13:50:30 +0000 (/etc/localtime) Received: from (9)mail021.syd.optusnet.com.au (mail021.syd.optusnet.com.au [200.39.20.161]) by blammo.monash.edu.au (Postfix) with ESMTP id 1F4AE12C002 for <pravin.shetty@inftech.monash.edu.au>; Tue, 23 Apr 2002 23:50:30 +1000 (EST) Received: from CO3025549A (10) (c16494.frank1.vic.optusnet.com.au [200.39.205.113])

  15. SMTP Headers by mail021.syd.optusnet.com.au (8.11.1/8.11.1) with SMTP id g3NDoRi15920 for <pravin.shetty@infotech.monash.edu.au>; Tue, 23 Apr 2002 23:50:27 +1000 Date: Tue, 23 Apr 2002 23:51:34 +1000 From: Patrik <patrik@optushome.com> Subject: Questions To: pravin.shetty@infotech.monash.edu.au Message-id: <EFEOICAJMKDCOLDIMNJNCEBACAAA.patrik@optushome.com> MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) Content-type: MULTIPART/MIXED; BOUNDARY="Boundary_(ID_DI+xGCWXZlChun9D5NMJlw)" Importance: Normal X-Priority: 3 (Normal) X-MSMail-priority: Normal Parts/Attachments:

  16. SMTP Model Local MTA MTA Relay Local MTA User Agent User Agent Processing Queue Processing Queue Mailboxes

  17. The SMTP Model • MTA: A mail transfer agent exchanges mail over a TCP/IP connection • System administrator is responsible for setting up the MTA • SMTP defines a MTA that implements a system based upon the spooling of messages.

  18. SMTP • First proposed in RFC821 • Later updated in RFC822 – replaced X.400 • Commands HELO client identifies itself MAIL/RCPT identifies originator and recipient DATA for sending the contents of the mail QUIT terminates the mail exchange RSET aborts a transfer and resets both the ends VRFY to verify the address without actually sending NOOP forces server to respond with OK EXPN expands a mailing list TURN lets client and server switch roles

  19. Mailing Lists • To send mail to a group of users, mailing lists are often used. • A mail server is needed to distribute the mail messages to members of a mailing list. • List can be manually created, or may be automatically maintained.

  20. Mailing Lists • Listservers maintaining automated lists receive mail messages from new list members requesting that they be added to the list. eg. subscribe cse3153 Mailing Lists • List members can also remove themselves from the list. eg. unsubscribe cse3153 Messages will be sent to all members of the list when e-mail is sent to the listname email address on the computer that is hosting the list. eg. cse3153@abacus.csse.monash.edu.au

  21. Terminal Connectivity • Allows remote users to log into computers that are attached to the network. • Users can be located anywhere that there is a network connection. • As if they were sitting at a terminal that was physically attached to that computer.

  22. File Transfer Moving files from one computer Moving files from one computer To another over the Internet To another over the Internet Assign1.doc Assign1.doc FTP COMPUTER A FTP Server COMPUTER B FTP Client

  23. Anonymous ftp • To use ftp, a user normally must identify themselves with a username and password. • Having accounts for all possible users is impractical. • An anonymous user account is maintained on many ftp servers.

  24. Anonymous ftp • The anonymous account is restricted to certain areas of the server and will normally have restricted privileges (e.g. may only be permitted to read and not write). • Most systems require the user's e-mail address to be typed instead of a password.

  25. Anonymous ftp • Many ftp servers use the account ftp (its easier to type). • Most WWW browsers support ftp as a built in function making it easy to use file transfer

  26. News • A network of news servers around the Internet implements the Network News Transfer Protocol (NNTP). These systems support a special-interest group type of information service.

  27. News • Messages can be posted to a news group and will then be broadcast to all news servers over a period of time.

  28. News • News messages can be read by anyone using a news client that is attached to a news server. • Most WWW browsers have NNTP plug-in applications

  29. HTML • Hyper Text Markup Language • a simple markup language used to create hypertext documents that are portable from one platform to another

  30. HTML • HTML documents are SGML documents • ISO Standard 8879:1986 Information Processing Text and Office Systems; Standard Generalized Markup Language (SGML)

  31. HTML • HTML describes the structure and organization of a document • It only suggests appropriate presentations of the document when processed • Tags define the start and end of headings, paragraphs, lists, character highlighting and links

  32. URL - Uniform Resource Locator • A link or pointer to an object or resource • Could be a file, a HTML document on a remote system etc

  33. HTML • HTML was developed as part of the World Wide Web - a concept that was initiated at the CERN Laboratories (European Particle Physics Laboratories) • Web sites have home pages • the first point of access • These point to other pages via URLs • hypertext pointing to address of the next page

  34. Browsers • Applications that connect to WWW servers • Send requests to the servers and receive responses in the form of web pages. • NCSA Mosaic, Lynx, Internet Explorer, Netscape Navigator.

  35. Virtual directory structure Directory Indexing Security Access control and user authentication Secure server chroot server Kereberos,MD5 authentications Image maps CGI Configurations Virtual Hosting Logfile rotations Starting, stopping, and restarting the daemon Multiple DirectoryIndex KeepAlive Redirect Directives Server-side includes HTTPD AdministrationRef: http://hoohoo.ncsa.uiuc.edu/docs/tutorials/

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