internet services some samples: email, login, file transfer, news document distribution, web...

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:

Sendmail (Unix), MS-Exchange (NT),

Netscape Messaging Server (Unix, NT)

Terminal Emulation

Port: 23 (uses Telnet Protocol)

Clients: telnet

Servers: telnetd

Port: 22

Clients: ssh

Servers: sshd

File Transfer

Uses File Transfer Protocol

Port: 21

Clients: ftp

Servers: ftpd (Unix), IIS (NT and Windows)

News

Uses Network News Transfer Protocol

Port: 119

Clients: MS-Outlook, Netscape Collabra

Servers: nntpd(Unix)

Electronic Documents

Gopher Protocol

Port: 70

Clients: wingopher

Servers: IIS

Web Services

Uses HTML Protocols

port: 80

Clients: Netscape Navigator, MS IE

Servers: IIS for Windows Platform, Apache Tomcat for Java Platform

With each of the preceding,

multiple clients may communicate with

a single server

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

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

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.

Mail servers

Mail clients

Received: from Received: from (2)(2) ALPHA8.MONASH.EDU.AUALPHA8.MONASH.EDU.AU by by (1)(1) silas.monash.edu.au silas.monash.edu.au (8.9.3/1.1.29.3/16Feb01-1022AM) id XAA0000955685; Tue, 23 Apr 2002 23:50:56 (8.9.3/1.1.29.3/16Feb01-1022AM) id XAA0000955685; Tue, 23 Apr 2002 23:50:56 +1000 (EST)+1000 (EST)

Received: from Received: from blammo.monash.edu.aublammo.monash.edu.au ([129.179.1.74]) by ([129.179.1.74]) by (3)(3) vaxh.monash.edu.auvaxh.monash.edu.au (PMDF V5.2-31 #39306) with ESMTP id (PMDF V5.2-31 #39306) with ESMTP id <01KGX6J1JA328WW4SY@vaxh.monash.edu.au> for <01KGX6J1JA328WW4SY@vaxh.monash.edu.au> for pravin.shetty@silas.monash.edu.au; Tue, 23 Apr 2002 23:50:48 +1000pravin.shetty@silas.monash.edu.au; Tue, 23 Apr 2002 23:50:48 +1000

Received: from blammo (unknown [127.0.0.1]) by Received: from blammo (unknown [127.0.0.1]) by (4)(4) localhost (Postfix) with localhost (Postfix) with ESMTP id 5425712C002 for <pravin.shetty@silas.monash.edu.au>; Tue, 23 Apr ESMTP id 5425712C002 for <pravin.shetty@silas.monash.edu.au>; Tue, 23 Apr 2002 13:50:43 +0000 (/etc/localtime)2002 13:50:43 +0000 (/etc/localtime)

Received: from Received: from mail1.monash.edu.aumail1.monash.edu.au (bigted.monash.edu.au [129.179.11.60]) by (bigted.monash.edu.au [129.179.11.60]) by (5)(5) blammo.monash.edu.au (Postfix) with ESMTP id 14A8512C002 for 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)<pravin.shetty@silas.monash.edu.au>; Tue, 23 Apr 2002 23:50:43 +1000 (EST)

Received: from Received: from ALPHA1.MONASH.EDU.AUALPHA1.MONASH.EDU.AU ([129.179.1.1]) by ([129.179.1.1]) by (6)(6) mail1.monash.edu.au (Netscape Messaging Server 4.15) with ESMTP id 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 GV0X4I00.NBA for <pravin.shetty@mail1.monash.edu>; Tue, 23 Apr 2002 23:50:42 +1000+1000

SMTP Headers

Received: from Received: from (8)(8) blammo.monash.edu.au blammo.monash.edu.au ([129.179.1.74]) by ([129.179.1.74]) by (7)(7) vaxc.monash.edu.au vaxc.monash.edu.au (PMDF V6.1 #39306) with ESMTP id (PMDF V6.1 #39306) with ESMTP id <01KGX6IRZ3MQ922MOH@vaxc.monash.edu.au> for <01KGX6IRZ3MQ922MOH@vaxc.monash.edu.au> for pravin.shetty@mail1.monash.edu (ORCPT pravin.shetty@inftech.monash.edu.au); pravin.shetty@mail1.monash.edu (ORCPT pravin.shetty@inftech.monash.edu.au); Tue, 23 Apr 2002 23:50:31 +1000Tue, 23 Apr 2002 23:50:31 +1000

Received: from blammo (unknown [127.0.0.1]) by localhost (Postfix) with ESMTP id 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 762F512C002 for <pravin.shetty@inftech.monash.edu.au>; Tue, 23 Apr 2002 13:50:30 +0000 (/etc/localtime)13:50:30 +0000 (/etc/localtime)

Received: from Received: from (9)(9) mail021.syd.optusnet.com.au mail021.syd.optusnet.com.au (mail021.syd.optusnet.com.au (mail021.syd.optusnet.com.au [200.39.20.161]) by blammo.monash.edu.au (Postfix) with ESMTP id 1F4AE12C002 [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)for <pravin.shetty@inftech.monash.edu.au>; Tue, 23 Apr 2002 23:50:30 +1000 (EST)

Received: from CO3025549A Received: from CO3025549A (10)(10) ( (c16494.frank1.vic.optusnet.com.au c16494.frank1.vic.optusnet.com.au [200.39.205.113])[200.39.205.113])

SMTP Headers

by mail021.syd.optusnet.com.au (8.11.1/8.11.1) with SMTP id g3NDoRi15920 for 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, <pravin.shetty@infotech.monash.edu.au>; Tue, 23 Apr 2002 23:50:27 +1000 Date: Tue, 23 Apr 2002 23:51:34 +100023 Apr 2002 23:51:34 +1000From: Patrik <patrik@optushome.com>From: Patrik <patrik@optushome.com>Subject: QuestionsSubject: QuestionsTo: To: pravin.shettypravin.shetty@infotech.monash.edu.au@infotech.monash.edu.auMessage-id: <EFEOICAJMKDCOLDIMNJNCEBACAAA.patrik@optushome.com>Message-id: <EFEOICAJMKDCOLDIMNJNCEBACAAA.patrik@optushome.com>MIME-version: 1.0MIME-version: 1.0X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)Content-type: MULTIPART/MIXED; Content-type: MULTIPART/MIXED; BOUNDARY="Boundary_(ID_DI+xGCWXZlChun9D5NMJlw)"BOUNDARY="Boundary_(ID_DI+xGCWXZlChun9D5NMJlw)"Importance: NormalImportance: NormalX-Priority: 3 (Normal)X-Priority: 3 (Normal)X-MSMail-priority: NormalX-MSMail-priority: NormalParts/Attachments:Parts/Attachments:

SMTP Headers

SMTP Model

User Agent Local MTA

Processing Queue Processing Queue

MTA Relay Local MTA

Mailboxes

User Agent

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.

SMTP

First proposed in RFC821 Later updated in RFC822 – replaced X.400 Commands

HELO client identifies itselfMAIL/RCPT identifies originator and recipientDATA for sending the contents of the mailQUIT terminates the mail exchangeRSET aborts a transfer and resets both the endsVRFY to verify the address without actually sendingNOOP forces server to respond with OKEXPN expands a mailing listTURN lets client and server switch roles

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.

Mailing Lists

Listservers maintaining automated lists receive mail messages from new list members requesting that they be added to the list.eg. subscribe cse3153Mailing Lists

List members can also remove themselves from the list.eg. unsubscribe cse3153Messages 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

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.

Moving files from one computerTo another over the Internet

FTPAssign1.doc Assign1.doc

COMPUTER AFTP Server

COMPUTER BFTP Client

Moving files from one computerTo another over the Internet

File Transfer

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.

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.

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

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.

News

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

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

HTML

Hyper Text Markup Languagea simple markup language used to

create hypertext documents that are portable from one platform to another

HTML

HTML documents are SGML documents

ISO Standard 8879:1986 Information Processing Text and Office Systems; Standard Generalized Markup Language (SGML)

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

URL - Uniform Resource Locator

A link or pointer to an object or resourceCould be a file, a HTML document on a

remote system etc

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 pagesthe first point of access

These point to other pages via URLshypertext pointing to address of the next

page

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.

HTTPD AdministrationRef: http://hoohoo.ncsa.uiuc.edu/docs/tutorials/

Virtual directory structure

Directory Indexing Security

Access control and user authentication

Secure serverchroot serverKereberos,

MD5 authentications Image maps

CGI Configurations Virtual Hosting Logfile rotations Starting, stopping, and

restarting the daemon Multiple DirectoryIndex KeepAlive Redirect Directives Server-side includes