Session 3

SESSION 3 - NETWORK TERMINOLOGIES II
=====================================


PORTS
======


A port is an endpoint of communication in an operating system. In the computer networking system a computer or a program connects and run the services on the Internet via a port. They are the gateways through which we access any service of any system.

THere are 2 TYpes of Ports Basically-

1. Hardware or Physical Ports - The ports which helps to connect the hardware components to our computer.These are the ports which are tangible and we can see and use the into a particular system. For eg. USB Port, HDMI, VGA Port.

2. Virtual or Logical Ports -  These are those ports which are not tangible and used to run a service in a Computer Networking System. For every service or protocol there is a unique port number assigned to it which helps in processing it. SO these are the ports which are virtually located in a system or a machine to access some services of the system but is not visible and virtually located.

There are a total of 65,535 POrts in a particular system.

Categories of Virtual and Logical Ports
=========================================

1. Well KNown and Pre-defined Ports - THese are those which are used for all the well knowned Services like which are used all over the globe.
EG.	FTP - 21
	HTTP - 80
	HTTPS - 443
http://www.facebook.com
	user : hgfhgg
	password : hggfd
https://www.facebook.com

	SMTP - 25
	POP3 - 110
	UDP - 53
	SSH - 22
	TELNET - 23

Range - 0 - 1023


2. Registered Ports - THese ports are those which are basically used by software organizations to run there services.

Eg.	MYSQL - 3306
	ITUNES - 1609
	MS-RDP - 3389
	ORACLE - MYSQL - 3306
	DARK COMET - 1604
	Team Viewer - 1609

3. Dynamic or Standalone Ports - THese ports are those which are used by anyone for there personal purposes.
For eg . 48,897

Range Of Ports
===============

WEll KNown Ports - 0-1023
Registered Ports - 1024 - 41,951
Dynamic Ports - 41,952-65,535

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

DNS
====

THE COMPUTER ONLY UNDERSTANDS THE LANGUAGE OF NUMBERS.
CHROME - "WWW.FACEBOOK.COM"
Language - Binaries - 0&1

Domain Name System is a Technology which converts a Domain Name into IP Address or a Number and Vice Versa.
Because it is difficult to learn a IP Address for a website for a layman. for eg. learning "247.116.25.195" for "www.google.com" .

"Ping" - "ping www.google.com"

"Tracert" - Trace Routes of the desitination with hops.

https://www.youtube.com/watch?v=2ZUxoi7YNgs


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


PROXIES AND VPN
=================

PROXY / PROXY SERVERS
======================
Proxy are the Dummy Servers which helps us by allocating an IP Address of themselves to us which is for temporary basis.
It acts as a middle man between DNS server and client accessing it.
THey alocate a IP Address of any location, and give us the permission to access the web service which is blocked.

To find out the loaction of a Global IP - "ip2location.com"

Proxies are of 3 Types
========================

1. Web Based Proxy or Proxy Servers - These are the Websites which are acting as a Proxy Server and allows to act as a intermediater between client and server.
For eg. - kproxy.com
		  ninja proxy etc.

2. Web Extension Based Proxy - THese are the Proxy Servers Client Agents which are enabled in our browser and helps to as behaving like a proxy dummy server.

For eg. Anonymox, Hola Proxy Extension etc.

3. Network Based Proxy -


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


VPN - VIRTUAL PRIVATE NETWORK
==============================
Virtual Private Network is more advanced technology which allows authorized clients to access the Virtually Created Network which will be safe and set the anonymity of a person. They are most advanced then proxies and basically a new virtual network created by organizations or anyone for there personal usage.

THey are only can be accessed by authorized people only usually in corporates for accessing there confidential resources..

More Functionalities that Proxies:
= Tunneling of data - So that there can be a secret passage which will not be known to anyone.
= Encryption of Data- It encrypts or make the data in the unreadable format.
= It gives you better functionalities of networking.
= Authorization and Authentication - Only authorized people can access it.

Eg. PROXPN, VPNBOOK.COM , free of cost


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

Standardisation Followed for commiunication into a Particular Network

OSI REFERENCE MODEL
====================

1. Physical Layer - Wired / Wireless, Bitwise conversion of data
2. Data Link Layer- MAC Addressing
3. Networking Layer - LOgical Addressing and IP Fragmentation
4. Transport Layer - Define the Port Addressing and Routing Architecture
5. Session Layer - Existance of a particular Session created by the Application.
6. Presentation Layer - Bit Conversion and Fragmentation of data packets
7. Application Layer - UI of any application -Whatsapp etc.

or

Physical Layer - Way of transmitting the day, - peripherals
Data Link Layer - Identifies the Hardware Address - MAC Address, Fragmentation and De-fragmentation of data
Network Layer - Logical Address - IP Address, Topologies, TCP/UDP
Transport Layer - Routing Mechanism, Port Addressing
Session Layer - TimeStamp of transmitting the data, QOS
Presentation Layer - Works on Segmentation as well as Window Framing
Application Layer - User Interface of the Application


Not Feasable
------------------------------------------------------------------------

TCP/IP MODEL
=============

1. Physical Layer / Network INterface = Physical + Data Link Layer
2. Network Layer / INternet Layer
3. TRansport Layer
4. Application Layer = Session + Presentation + Application Layer

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

WEB TECHNOLOGY BASICS
======================

1. Web Hosting Space - ICANN - GoDaddy, Bigrock etc.
2. Domain Name - .com/.in/.net
3. Database - Where all the data get stored in a server
4. Server Type - Windows based servers, Linux Servers
5. Clients and Server Architecture
6. WEb Technologies - HTML , PHP , JSP , ASP etc.

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

TASK
=====

1. How does Search Engine Works? Spiders? Crawlers?
2. https://www.google.co.in
	https
	:
	//
	www
	.
	google
	.
	co
	.
	in
3. Create a Table of 10 Well Keown Ports and Registered Ports.
4. Comprision between OSI and TCP/IP Model.