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.com
Subject: 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
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
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 ; 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
; 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 ; Tue, 23 Apr 2002 23:50:42
+1000
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
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 ; 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 ; Tue, 23 Apr 2002 23:50:30 +1000 (EST)
Received: from CO3025549A (10) (c16494.frank1.vic.optusnet.com.au
[200.39.205.113])
SMTP Headers
by mail021.syd.optusnet.com.au (8.11.1/8.11.1) with SMTP id g3NDoRi15920 for
; Tue, 23 Apr 2002 23:50:27 +1000 Date: Tue,
23 Apr 2002 23:51:34 +1000
From: Patrik
Subject: Questions
To: pravin.shetty@infotech.monash.edu.au
Message-id:
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:
SMTP Model
User Agent Local MTA MTA Relay Local MTA User Agent
Processing Queue Processing Queue Mailboxes
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 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
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 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
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.
File Transfer
Moving files from one computer
To another over the Internet
Assign1.doc Assign1.doc
FTP
COMPUTER A COMPUTER B
FTP Server FTP Client
Anonymous ftp
Touse 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 Language
a 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 resource
Could 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 pages
the first point of access
These point to other pages via URLs
hypertext 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 Administration
Ref: http://hoohoo.ncsa.uiuc.edu/docs/tutorials/
Virtual directory CGI Configurations
structure Virtual Hosting
Directory Indexing Logfile rotations
Security Starting, stopping, and
Access control and restarting the daemon
user authentication Multiple DirectoryIndex
Secure server KeepAlive
chroot server Redirect Directives
Kereberos, Server-side includes
MD5 authentications
Image maps