Www.infotech.monash.edu Basic Internet Services eMail, login, file transfer, news, document...

www.infotech.monash.edu

Basic Internet Services

eMail, login, file transfer, news,

document distribution, Web services

Service management


2

eMail

Active message delivery – “push” technology

TCP Port: 25

uses Simple Mail Transfer Protocol (SMTP)

Clients:• mailx, pegasus, MS Outlook, Netscape Messenger, Mozilla

Thunderbird…

Servers:• Sendmail (Unix), MS-Exchange, Netscape Messaging Server,

Mailman, Maiser…


3

Terminal Emulation

• uses Telnet protocol• TCP Port: 23• Clients: telnet• Servers: telnetd (Unix)• Now rarely used (for security reasons)


4

Secure Terminal Emulation

• Secure Shell protocol (ssh)• Uses TCP port 22• Handles session key negotiation and encryption of traffic• Also possible to do encapsulation of data from other ports

on client and server machines (port forwarding)• Client: ssh, putty, teraterm• Server: sshd (unix)


5

File Transfer

• Uses File Transfer Protocol (FTP)• Port: 21• Clients: ftp • Servers: ftpd (Unix), embedded in IIS (Win32)


6

Secure File Transfer

• Secure File Copy (scp)• Secure File Transfer Protocol (sFTP)• Usually implemented as cp or ftp inside ssh encapsulated

session• Clients: winSCP (win32), Fugu (Mac OS/X)• Servers: sshd (UNIX)


7

News

• Passive messaging - “pull technology”• Uses Network News Transfer Protocol• Port: 119• Clients: MS Outlook, Netscape Collabra, Mozilla Thunderbird• Servers: nntpd(Unix),


8

Web Services

• Uses HTML for message format and HTTP for message transport

• port: 80 (or 8080) or 445 for secure HTTP• Clients: Mozilla firefox, Netscape Navigator, MS

InternetExplorer, Opera• Servers: IIS (win32), apache (unix & win32), tinyhttpd


Client/Server, 1-to-Many

With each of the preceding,

multiple clients may communicate with

a single server


10

File Transfer Protocol (FTP)


11

• 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

eMail


12

e.g. mail [email protected]

Subject: How is the Project?

Message

-----------------------------------------------

Hi,

I got your last message....

.....

etc

eMail (cont’d)


13

eMail (cont’d)

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

MTA MTA

MTA

mailservers

Mail clients


14

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 <[email protected]> for [email protected]; 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 <[email protected]>; 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 <[email protected]>; 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 <[email protected]>; Tue, 23 Apr 2002 23:50:42 +1000

eMail -- SMTP Headers


15

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

Received: from blammo (unknown [127.0.0.1]) by localhost (Postfix) with ESMTP id 762F512C002 for <[email protected]>; 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 <[email protected]>; Tue, 23 Apr 2002 23:50:30 +1000 (EST)

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



16

by mail021.syd.optusnet.com.au (8.11.1/8.11.1) with SMTP id g3NDoRi15920 for <[email protected]>; Tue, 23 Apr 2002 23:50:27 +1000 Date: Tue, 23 Apr 2002 23:51:34 +1000From: Patrik <[email protected]>Subject: QuestionsTo: [email protected]: <[email protected]>MIME-version: 1.0X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)Content-type: MULTIPART/MIXED; BOUNDARY="Boundary_(ID_DI+xGCWXZlChun9D5NMJlw)"Importance: NormalX-Priority: 3 (Normal)X-MSMail-priority: NormalParts/Attachments:



17

eMail – the SMTP Model

User Agent

Local MTA

Processing Queue Processing Queue

MTA Relay Local MTA

Mailboxes

User Agent


18

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.


19

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


20

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.


21

Mailing Lists

• Listservers maintaining automated lists receive mail messages from new list members requesting that they be added to the list.

• eg. subscribe FIT2018_Notices• Self registration method…


22

Mailing Lists

• List members can also remove themselves from the list.• eg. unsubscribe FIT2018_Notices• Messages will be sent to all members of the list when e-mail

is posted to the listname email address on the computer that is hosting the list. eg. [email protected]


23

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.

• Security implications: the conversation may not be private if using an internet connection


24

Terminal Connectivity (cont’d)

• eg. terminal session accessing the library computer • library.monash.edu.au (before 2000… now uses web

interface)


25

COMPUTER AFTP Server

COMPUTER BFTP Client

Assign1.doc Assign1.doc

File Transfer Protocol (FTP)

• Moving files from one computer To another over the Internet

GET

PUT


26

FTP -- 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


27

FTP -- 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.

• 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


28

News

• All 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.

• Servers use peer-to-peer transfer (news feed)


29

News

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


30

• News messages can be read by anyone using a news client that is attached to a news server.

• Most WWW browsers and email readers have NNTP plug-in applications

News


31

HyperText Transfer Protocol (HTTP)

• HyperText Markup Language• a simple markup language used to create hypertext

documents that are portable from one platform to another• HTML documents are SGML documents• ISO Standard 8879:1986 Information Processing Text and

Office Systems; Standard Generalized Markup Language (SGML)


32

HTTP (cont’d)

• 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


33

<html>

<head>

<title>CPE2009 Lectures</title>

</head>

<body>

<table width=“100%” cellspacing=“0“ cellpadding="0" border="0" >

etc…

HTTP (cont’d)


34

HTTP (cont’d)


35

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

• Virtual directory structure• Directory Indexing• Security

– Access control and user authentication

– Secure server– chroot server– Kereberos,

MD5 authentications• Imagemaps

• CGI (Common Gateway Interface) Configurations

• Virtual Hosting• Logfile rotations• Starting, stopping, and

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


End…

Www.infotech.monash.edu Basic Internet Services eMail, login, file transfer, news, document...

Documents

Transcript of Www.infotech.monash.edu Basic Internet Services eMail, login, file transfer, news, document...