Transcript Mirela Walczak prezentacja

BASIC INTERNET PROTOCOLS:
http, ftp, telnet.
Mirela Walczak
Content :
Key Words
Introduction
Internet Protocol Suite
Client Server Model
OSI Model
FTP Protocol
HTTP Protocol
TELNET Protocol
Key Words:
•
•
•
•
•
•
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Port
Host
Control stream
Proxy
SSL- secure sockets layer
Client
Server
What is protocol?
Is a convention or standard that controls or
enables the connection , communication and
data transfer between two computing
endpoints.
Internet Protocols Suite
The set of communication
protocols used for Internet and
other similar networks.
• Internet Protocol
IP
• Transmission Control Protocol
TCP
OSI Model
O
S
I
• The Open Systems
Interconnection
Reference Model
• OSI Reference
Model
• OSI Model
• OSI seven layer
model
TCP/IP Model – OSI Model
Client Server Model
Software
architecture model
distinguishes Client
system from Server
system, which
communicate over
a computer
network.
The qualities characteristic for:
Server:
 Passive
 It waits for the
requests from the
client
 When the request is
received – server
process it and send an
answer to the client
Client:
Active
It sends the request
to server
It is waiting for the
answers from the
server
File Transfer Protocol
Is a network protocol used for
transfer data from one computer to
another through a network such as
Internet.
Advantages of FTP
• FTP operates on two ports: 21, 20
• Provides two different transfer mode:
Active client mode
Passive server mode
• Servers can have „anonymous FTP” access
• Two formats on which data can be send:
ASCII mode-American Standard Code for Information
Interchange
BINARY mode
BINARY mode
ASCII mode
Disadvantage of FTP
• FTP is a high latency protocol for e.g to begin a
transfer of data it has to be used many
comands.
• Passwords and file contents are sent in clear
text, allowing unwanted eavesdropping.
• It is possible to tell a server to send data to an
arbitrary port of a third computer.
The objectives of FTP:
• To promote sharing of files (computer
programs and/or data).
• To encourage indirect or implicit use of
remote computers.
• To shield a user from variations in file storage
systems among different hosts.
• To transfer data reliably, and efficiently.
HyperText Transfer Protocol
Is a communication protocol for the transfer
of information on the Internet.
World Wide Web Consortium
Type
Consortium
Founded
October 1994
Founder
Tim Berners-Lee
Headquarters
MIT/CSAIL in USA
ERCIM in France
Keio University in
Japan
and many other
offices around the
world
Website
www.w3.org -History
Offices of the current Internet
Engineering Task Force Secretariat
HTTP request method
• HEAD-Asks for the response identical to the one that would
correspond to a GET request, but without response body.
• GET-Requests a representation of the specified resource.
• POST-Submitt data to be processed (e.g. from a HTML form)
to the identified resource.
• PUT-Uploads a representation of the specified resource.
• DELETE-Deletes the specified resource.
• TRACE-Echoes back the received request, so that a client can
see what intermediate servers are adding or changing in the
request.
• OPTIONS-Returns the HTTP methods that the server
supports.
• CONNECT-For use with a proxy that can change to being an
SSL tunnel.
HTTP Versions
• HTTP/0.9
Support only one command GET and omits the header.
• HTTP/1.0
This is the first protocol revision to specify its version in
communications.
• HTTP/1.1
Current version with persistent connection.
Allows pipelining and multiple request at the same time.
Works well with proxies
• HTTP/1.2
Version from the 1995, later subsumed by the experimental
HTTP Extension Framework
Telecommunication
Network Protocol
Is a network protocol
used on the Internet or
local area network
(LAN) connections.
TELNET security
Three main reasons why ..........?
• Does not encrypt any data sent over the
connection (including passwords).
• Does not ensure that communication is
carried out between the two desired hosts,
and not intercepted in the middle.
•The packets allow easily obtain login and
password information.
Current Status
• TELNET was replaced by SSH (Secure shell
protocol with high level of encryption).
• Popular in enterprise networks to access host
applications.
• Is also heavily used for games played over the
Internet, as well as talkers.
• Cannot be used as a tunneling protocol.
• Should not be used on networks with Internet
connection.
SUMMARY
• PROTOCOLS are very important in successful
communication.
• INTERNET PROTOCOL SUITE consist of two protocols
IP and TCP. They are responsible for transmission
data.
• OSI MODEL is an abstract description for layered
communication and computer’s network protocol
design. Consist of 7 seven layers.
• CLIENT SERVER MODEL is responsible for exchanging
information between client and server .
FILE TRANSFER PROTOCOL
• There are two computers involved in an FTP
transfer: a server and a client.
• Any software company or individual
programmer is able to create FTP server or
client software because the protocol is an
open standard.
• There are many existing FTP client and server
programs, and many of these are free.
HYPERtext TRANSFER PROTOCOL
• Its original purpose was to provide a way to
publish and retrieve HTML pages.
• Development of HTTP was coordinated by the
World Wide Web Consortium and the Internet
Engineering Task Force.
• HTTP is a request/response protocol between
clients and servers.
• HTTP defines eight methods.
• HTTP versions: 0.9, 1.0, 1.1, 1.2
TELNET PROTOCOL
• Name is derived from the words
telecommunication network.
• It was developed in 1969.
• Provides general, bi-directional, 8-bit
communication.
• Client-server protocol with port 23.
• TELNET is not recommended for modern
systems from the point of view of computer
security.
Sources
• http://en.wikipedia.org/wiki/Main_Page
• http://www.demon.net/helpdesk/technicallib
rary/misc/telnet/images/telnet.gif
• http://www.cyfkr.edu.pl/~mfjawien/FZI/Wstepx1.html
• http://www.angelfire.com/ab7/gregsgrl85/ftp.
html
• http://www.cs.rpi.edu/academics/courses/fall
96/netprog/lectures/html/ftp/tsld002.htm