BASIC INTERNET PROTOCOLS: http, ftp, telnet.

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: • 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 OSI • 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

ASCII mode BINARY 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.

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/technicallibrary/misc/telnet/images/telnet.gif • http://www.cyf-kr.edu.pl/~mfjawien/FZI/Wstepx1.html • http://www.angelfire.com/ab7/gregsgrl85/ftp.html • http://www.cs.rpi.edu/academics/courses/fall96/netprog/lectures/html/ftp/tsld002.htm

BASIC INTERNET PROTOCOLS: http, ftp, telnet.