Application layer protocol

Application Layer Protocol

Amitava Nag

Assistant Professor

amitavanag.09@gmail.com

April 6, 2012

Amitava Nag (Academy of Technology) Application Layer Protocol April 6, 2012 1 / 37

Architecture of WWW

The WWW is a distributed client-server service, in which a clientusing a browser can access a service using a server.

Architecture of WWW

The WWW is a distributed client-server service, in which a clientusing a browser can access a service using a server.

The service provided is distributed over many locations called sites.

Architecture of WWW

Browser

Internet apps: application, transport protocols

Application Application layer Underlying

protocol transport protocol

email SMTP [RFC2821] TCP

remote terminal Telnet[RFC854] TCP

access

web HTTP [RFC2616] TCP

file transfer FTP [RFC959] TCP

Remote File Server NFS UDP/TCP

Web Page Identifier

Known as Uniform Resource Locator (URL)

Web Page Identifier

Encodes

Web Page Identifier

Encodes

- Access protocol to use

Web Page Identifier

Encodes

- Access protocol to use- Domain name of server

Web Page Identifier

Encodes

- Access protocol to use- Domain name of server- Protocol port number (optional)

Web Page Identifier

Encodes

- Access protocol to use- Domain name of server- Protocol port number (optional)- Path through servers file system (optional)

Web Page Identifier

Encodes

- Access protocol to use- Domain name of server- Protocol port number (optional)- Path through servers file system (optional)- Parameters (optional)

Web Page Identifier

Encodes

- Access protocol to use- Domain name of server- Protocol port number (optional)- Path through servers file system (optional)- Parameters (optional)- Query (optional)

Web Page Identifier

Encodes

- Access protocol to use- Domain name of server- Protocol port number (optional)- Path through servers file system (optional)- Parameters (optional)- Query (optional)

Formathttp: // hostname [: port] / path [; parameters] [? query]

Web and HTTP

Web page consists of objects

Web and HTTP

Object can be HTML file, JPEG image, Java applet, audio file,

Web and HTTP

Web page consists of base HTML-file which includes severalreferenced objects

Web and HTTP

Each object is addressable by a URL

Web and HTTP

Each object is addressable by a URL

Example URL:www.someschool.edu/someDept/pic.gif

HTTP Characteristics

Application level

Request / response paradigm

Application level

Stateless

Application level

Stateless

Permits bi-directional transfer

Application level

Stateless

Offers capability negotiation

Application level

Stateless

Support for caching

Application level

Stateless

Support for caching

Support for intermediaries

HTTP overview

HTTP overview ( continued )

Uses TCP :

HTTP client initiates TCP connection (creates socket) to (www.someschool.edu/ ) server on port 80 (default port number forHTTP).

Uses TCP :

HTTP server accepts TCP connection from client

Uses TCP :

HTTP messages (application-layer protocol messages) exchangedbetween browser ( HTTP client ) and Web server ( HTTP server )

Uses TCP :

HTTP messages (application-layer protocol messages) exchangedbetween browser ( HTTP client ) and Web server ( HTTP server )

TCP connection closed

HTTP connections

Nonpersistent HTTP Persistent HTTP

At most one object is sent over Multiple objects can be sent overa TCP connection. single TCP connection between

client and server.

HTTP/1.0 uses nonpersistent HTTP HTTP/1.1 uses persistentconnections in default mode

FTP: the file transfer protocol

transfer file to/from remote host

client/server model

client: side that initiates transfer (either to/from remote)

client/server model

server: remote host

client/server model

server: remote host

ftp: RFC 959

client/server model

server: remote host

ftp: RFC 959

ftp server: port 21

FTP overview

FTP:connections

Opening the control connection

Creating the data connection

FTP: separate control, data connections

FTP client contacts FTP server at port 21, specifying TCP astransport protocol

Client obtains authorization over control connection

Client browses remote directory by sending commands over controlconnection.

When server receives a command for a file transfer, the server opens aTCP data connection to client

After transferring one file, server closes connection.

Server opens a second TCP data connection to transfer another file.

Control connection: out of band

FTP server maintains state: current directory, earlier authentication

Remote Login: Telnet

TELNET is a general-purpose client-server application program

TELNET enables the establishment of a connection to a remotesystem in such a way that the local terminal appears to be a terminalat the remote system.

Figure:Local login

Figure:Remote login

Electronic Mail

Three major components:

Electronic Mail

Three major components:1 user agents

Electronic Mail

Three major components:1 user agents2 mail servers

Electronic Mail

Three major components:1 user agents2 mail servers3 simple mail transfer protocol: SMTP

Electronic Mail

Electronic Mail: mail servers

Mail Servers

mailbox contains incoming messages for user

Mail Servers

message queue of outgoing (to be sent) mail messages

Mail Servers

SMTP protocol between mail servers to send email messages

Mail Servers

client: sending mail server

Mail Servers

client: sending mail serverserver: receiving mail server

Electronic Mail: SMTP [RFC 2821]

uses TCP to reliably transfer email message from client to server, port25

direct transfer: sending server to receiving server

three phases of transfer

handshaking (greeting)

handshaking (greeting)transfer of messages

handshaking (greeting)transfer of messagesclosure

command/response interaction

commands: ASCII text

commands: ASCII textresponse: status code and phrase

messages must be in 7-bit ASCII

Scenario: Alice sends message to Bob

1 Alice uses UA to compose message and to bob@someschool.edu

2 Alices UA sends message to her mail server; message placed inmessage queue

3 Client side of SMTP opens TCP connection with Bobs mail server

4 SMTP client sends Alices message over the TCP connection

5 Bobs mail server places the message in Bobs mailbox

6 Bob invokes his user agent to read message

Figure: Alice sends message to Bob

Mail access protocols

SMTP: delivery/storage to receivers server

Mail access protocol: retrieval from server

Mail access protocol: retrieval from serverPOP: Post Office Protocol [RFC 1939]

authorization (agent < −− >server) and download

IMAP: Internet Mail Access Protocol [RFC 1730]

more features (more complex)

more features (more complex)manipulation of stored msgs on server

HTTP: Hotmail , Yahoo! Mail, etc.

Figure:Mail access protocols

Network Management

Management =

Network Management

Management = Initialization,

Network Management

Management = Initialization, Monitoring,

Network Management

Management = Initialization, Monitoring, Control

Network Management

Today: automated, reliable diagnosis, and automatic control are stillin a primitive stage

Network Management

Architecture: Manager, Agents and Management Information Base(MIB)

Network Management

Architecture: Manager, Agents and Management Information Base(MIB)

Observe that management-plane has a new interface to the networkdistinct from data and control-plane

Simple Network Management Protocol (SNMP)

SNMP is a framework for managing devices in an internet using theTCP/IP protocol suit

A manager, usually a lost that, controls and monitor a set ofagents,usually routers

The manager is a host that runs the SNMP client program.

The agent is a router or host that runs the SNMP server program

Figure:Mail access protocols

MANAGEMENT COMPONENTS

SNMP requires the use of two other protocols:

SNMP requires the use of two other protocols:1 Structure of Management Information (SMI) and

SNMP requires the use of two other protocols:1 Structure of Management Information (SMI) and2 Management Information Base (MIB)

Network management on the Internet is done through thecooperation of SNMP, SMI, and MIB.

Management Information Base(MIB)

MIB is a second component used in network management

Each agent has its own MIB, a collection of all the objects that themanager can manage.

Figure:Management Information Base, version 2 (MIB2)

SNMP is an application program that allows

SNMP is an application program that allows1 a manager to retrieve the value of an object defined in an agent;

SNMP is an application program that allows1 a manager to retrieve the value of an object defined in an agent;2 a manager to store a value in an object defined in an agent; and

SNMP is an application program that allows1 a manager to retrieve the value of an object defined in an agent;2 a manager to store a value in an object defined in an agent; and3 an agent to send an alarm message about an abnormal situation to the

manager

Figure:SNMP

The End

Application layer protocol

Engineering

GPS Tracker Communication Protocol - iconcox.in · - 2 - 1 Communication Protocol This document defines instructions about interface protocol on application layer of vehicles GPS

HDoS: An Application-Layer DoS Attack Towards HTTP/2 Protocol An Application-Layer DoS At… · also supposed to face application-layer DoS attacks. In this paper, we narrow our research

Simple Network Management Protocol · • The Simple Network Management Protocol (SNMP) Internet-standard protocol (application layer protocol) • Used for managing devices on IP

An Application Layer Protocol for Energy-Efﬁcient ...cssongguo/papers/bandaggregation15.pdf · 1 An Application Layer Protocol for Energy-Efﬁcient Bandwidth Aggregation with Guaranteed

Electrical Protocol and Application Layer Validation MIPI D PHY and M PHY Design

Introduction to HTTP The HyperText Transport Protocol is an ‘application-layer’ protocol for the ‘client/server’ paradigm

SMUCSE 4344 application layer. SMUCSE 4344 application vs. application-layer protocols application-layer protocol is just one piece –how the end hosts

Network Layer - Courses · • Link-layer (layer 2) ... • Only one protocol at the network layer. ... TCP IP Network Access Application protocol

Transmission Control Protocol / Internet Protocol (TCP/IP) Application Layer Transport Layer Internetwork Layer Network Interface Layer Parziale, Lydia,

Transport layer security protocol for SPWF01Sx module · March 2017 DocID027745 Rev 3 1/31 31 AN4683 Application note Transport layer security protocol for SPWF01Sx module Introduction

Chapter 2 Internet Protocol DoD Model Four layers: – Process/Application layer – Host-to-Host layer – Internet layer – Network Access layer

Transport Layer - Universitetet i oslo · Layer Transport Entity Network Layer Application Layer Transport Entity Network Layer Service Interface Transport Port Protocol IP: Message

Network Protocol. 2 Application layer protocol Transport layer protocol Network layer protocol Link layer protocol

I J I 1 LONWORKS’” Host Application Programmer’s Guide...Application layer The application layer, also known as the LONTALK Network Driver Protocol, is used by the host application

Chapter 2 Application Layerfunda/TEACHING/SP13/371/chap2.pdf · 2013. 1. 14. · Application Layer 2-16 Internet apps: application, transport protocols application layer protocol

Wireless Sensor Networks Akyildiz/Vuran 1 PROTOCOL STACK Application Layer Transport Layer Network Layer Link Layer Physical Layer Power Management Plane

Part 2: Application Layerweb.cse.ohio-state.edu/~champion.17/3461/Part2_App.pdfThe Web: the HTTP Protocol HTTP: HyperTextTransfer Protocol • Web’s application layer protocol •

The Application Layer - Pearsonwps.pearsoncustom.com/wps/media/objects/7457/7636833/... · 2009. 6. 16. · DNS is an application-layer protocol. The name-to-IP-address translation

Protocol Layers and Their Service Models · network applications and their application-layer protocols reside. The Internet’s application layer includes many protocols, such as

Transport layer security protocol for SPWF01Sx module · Transport layer security protocol for SPWF01Sx module ... 1 SSL/TLS protocol overview ... Transport layer security protocol