Networking fundamentals

Networking
Fundamentals
The Avi Sharma

Contents
• What is Network ?
• Types of networks
• OSI Model
• Protocols
• TCP/IP Model
• Network Equipments
• IP Address
• MAC Address
• Other Basic terms
• Networks Security
• Policies of Network Security

What is Network ?
• When two or more computers that are linked in a order to share resources
are known as Network.
• We can share files,informations,and any kind of data over a network.
• Examples of Network –
Internet , it connects millions of people all over the world and they can
share their resources like they can download and upload any kind of data
from any corner of the world.

Advantages Disadvantages
1. Resource Sharing 1. Initial Costs
2. Data Sharing 2. Heavy Maintenance
3. Access Control 3. Security Concerns
4. Data Security 4. Vulnerability attacks
5. Accuracy 5. Robustness

Types of networks
• There are different types of networks such as :
1. LAN – stands for Land area network. It covers a small area (1-10 kms).
they are used in a small area like a buildings ,halls, offices etc.
2. MAN – stands for Metropolitan Area Network. It covers a large area like
a city or town. MAN is a large form LAN. It spread up to (60 Kms).
3. WAN – stands for Wide Area Network. It covers a very large region. It can
spread up to a whole country or nation.

4. PAN stands for Personal area network. Network that enables
. communication between computer devices near a person.
Example – Laptop, Computer, and mobile etc.
5. CAN - stands for Campus area network. It is group of connected local area
networks within a certain geographical area. The size of CAN is
lesser than MAN or WAN.

OSI MODEL
Open System Inter-Connection Reference Model
It is a basic conception to understand the functioning a networking system. It has
various layers to describe different kind of processes performs in a network. We
can also say that these layers are the rules and regulations to establish a
connection between networks. It is developed by International Tele
communication Union [I.T.U]. It is necessary because pen-testing and hacking
is all about inter-connected networks.
It has divided into 7 layers –
Physical Layer, Data Link Layer, Network Layer, Transport Layer, Session Layer
Presentation Layer and Application Layer

Layers of OSI
1.Physical Layer - It is used to manages the operations of sending data over
the physical mediums. It is responsible for data to process.
It works on Hub, Repeater, Modem, Cables etc.
2.Data Link Layer - It manage the delivery of message from one node to
another node . The objective of this layer is to make
the physical layer secure without any errors.
3.Network Layer - It sends the data packets from one source to destination ,
this process is known as routing. It decide that which path
is best to send them.

Layers of OSI
4. Transport Layer - Transport layer provides services to application layer and
takes services from network layer and this layer is also
responsible for that transportation. It divides data into
parts known as segments which increases the speed.
5. Session Layer - The session layer is responsible for establishing,
managing, and terminating sessions between end-user
application processes.

Layers of OSI
6. Presentation Layer - This layer takes cares that data can be easily
understand by receiver and we can say that it works
as a translator.
7. Application Layer - An application layer is an abstraction layer that
specifies the shared communications protocols and
interface methods used by hosts in a communications
network.

Protocols
Protocols - A network protocol is an established set of rules that determine
how data is transmitted between different devices in the
same network. Sender and receiver do not understand the
proper communication without the protocols. Each and every
protocols has its own task to perform.
Some protocols which used during the networking -
1. Transmission Control Protocol (TCP/IP):
TCP and IP are separate protocols that work together to ensure data is
delivered to its destination within a network. IP obtains and defines the
address—the IP address—of the application or device the data must be sent
to. TCP is then responsible for transporting data and ensuring it gets
delivered to the destination application or device that IP has defined.

2. User Datagram Protocol (UDP): UDP is a protocol in which a data is
transmitted quickly between networks without any communication
channel. It works only when receiver send a request and order for a
response from the server. It increases the speed of data transfering.
3. Post office Protocol (POP): POP3 is designed for receiving incoming E-mails
from a mail server.
4. Simple mail transfer Protocol (SMTP): SMTP is designed to send and
distribute outgoing E-Mail.
5. File Transfer Protocol (FTP): FTP allows users to transfer files from one
machine to another. Types of files may include program files, multimedia
files, text files, and documents, etc.

6. Hyper Text Transfer Protocol (HTTP): HTTP is designed for transferring a
hypertext among two or more systems. HTML tags are used for creating
links. These links may be in any form like text or images. HTTP is designed on
Client-server principles which allow a client system for establishing a
connection with the server machine for making a request. The server
acknowledges the request initiated by the client and responds accordingly.
7. Telnet: Telnet is a set of rules designed for connecting one system with
another. The connecting process here is termed as remote login. The system
which requests for connection is the local computer, and the system which
accepts the connection is the remote computer.

Other Protocols
• Some Other Protocols
1.ARP (Address Resolution Protocol)
2.DHCP (Dynamic Host Configuration Protocol)
3.IMAP4 (Internet Message Access Protocol)
4.SIP (Session Initiation Protocol)
5.RTP (Real-Time Transport Protocol)
6.RLP (Resource Location Protocol)
7.RAP (Route Access Protocol)
8.L2TP (Layer Two Tunneling Protocol)
9.PPTP (Point To Point Tunneling Protocol)
10.SNMP (Simple Network Management Protocol)

TCP/IP Model
TCP/IP Model
The Transmission Control Protocol/Internet Protocol reference model is a layered
model developed by the Defense Project Research Agency(ARPA or DARPA) of the
United States as a part of their research project in 1960.
It helps you to determine how a specific computer should be connected to the
internet and how data should be transmitted between them. It helps you to create
a virtual network when multiple computer networks are connected together. The
purpose of TCP/IP model is to allow communication over large distances.

Layers of TCP/IP
• There are 4 types of layers –
1. Application Layer – It deals with the communication of the whole data message.
The Application layer provides an interface between the
network services and the application programs.
2. Transport Layer – It is responsible for transporting data and setting up communication
between the application layer and the lower layers.
3. Network Layer - It deals with data in the form of datagrams or data packets. This layer
mainly performs the logical addressing of the data packets by adding
the IP(Internet Protocol) address to it.

4. Network Interface/Physical Layer - It is used to manages the operations of
sending data over the physical mediums. In this l

OSI vs TCP/IP
• OSI model is developed by ISO (International Standard Organization),
whereas TCP Model is developed by ARPANET (Advanced Research Project
Agency Network).
• OSI Model is a logical and conceptual model that defines network
communication and TCP/IP helps you to determine how a specific
computer should be connected to the internet.
• OSI has 7 layers whereas TCP/IP has 4 layers.
• OSI header is 5 bytes whereas TCP/IP header size is 20 bytes.
• OSI follows a vertical approach whereas TCP/IP follows a horizontal
approach.

Network Equipments
• To connect two or more computer over a network we need some
networking equipments, such as –
1. Modem - It is a device which converts digital signal to analog signal and
it also converts analog signal to digital signals, this whole process is
known as modulation and demodulation. It increases the speed of data
transmission.

2. Hub - it is a device which connect many computers in a network
physically.
3. Switch - is networking hardware that connects devices on a computer
network by using packet switching to receive and forward data to the
destination device.
4. Router – it is device which connects the devices and send data packets
from one source to another source from the best route which has less
traffic, and this process is called routing.

5. Gateway – It is a gate of network is networking hardware that connects
devices on a computer network by using packet switching to receive and
forward data to the destination device.
6. Network Interface Card (NIC)– It is a hardware component which is
installed in a system for establishing a connection between devices. It is
also known as Network Adapter. NIC allows both wired and wireless
communications. It consist MAC address.

IP Address
Internet Protocol(IP) Address
An IP address is a unique address that identifies a device on the internet or a local
network. IP stands for "Internet Protocol," which is the set of rules governing the
format of data sent via the internet or local network. We can check our system IP
by entering “ipconfig” command in command prompt.
IP address space is managed globally by the Internet Assigned Numbers
Authority (IANA)
Versions Of IP Addresses :
1. IPv4 : It is a 32 bit binary number. IPv4 was the first version of IP. it is considered
the primary Internet Protocol and carries 94% of Internet traffic. Eg. –
192.168.00.00
2. IPv6 : It is a128 bit binary number. IPv6 is an alphanumeric addressing method.
It is the most recent version. Eg.- 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

MAC Address
Media Access Control(MAC) Address
MAC address is a unique identifier that is assigned to a NIC (Network
Interface Controller/ Card). It consists of a 48 bit or 64-bit address, which
is associated with the network adapter. MAC address can be in
hexadecimal format. The full form of MAC address is Media Access Control
address. MAC address is a unique number which is used to track a device
in a network.
Eg.-

Other basic terms
• Subnetting is the practice of dividing a network into two or smaller
networks. It increases routing efficiency, which helps to enhance the
security of the network and reduces the size of the broadcast domain.
• A firewall is a security device — computer hardware or software — that
can help protect your network by filtering traffic and blocking outsiders
from gaining unauthorized access to the private data on your computer.
• The Domain Name System (DNS) is the phonebook of the Internet.
Humans access information online through domain names, like
facebook.com or google.com. Web browsers interact through Internet
Protocol (IP) addresses. DNS translates domain names to IP addresses so
browsers can load Internet resources.

Networks Security
• The process of securing network from unauthorized access and missuse is
known as network security.
• It is important for home networks as well as in the business world because
they have one or more wireless routers, for circulating internet connection
within the institution which could be exploited if not properly secured. If
someone can get unauthorized access to your network then he will able to
perform bad operations all over the network.
• It is also very necessary to secure our networks for maintain privacy and
avoid data leakage.
• The study of securing networks and networking environments , is
Known as Information security or Cyber Security.

• Elements of network security –
1. Physical security - Physical security controls are designed to prevent unauthorized
personnel from gaining physical access to network components such as routers,
cabling cupboards and so on. Controlled access, such as locks, biometric
authentication and other devices, is essential in any organization.
2. Network Access Control -To ensure that potential attackers cannot gain access to
your network, control policies need to be in place for both users and devices in
which, only authorized users are allowed to gain access to the netowork.
3. Network Authentication If the user's identity has been stored by the server,
entering a valid username and password completes the connection.
After verifying his identity then only he/she will get access to that system.
Elements of network security

• Network Policy - Network policy is a collection of rules that govern the
behaviors of network devices. To achieve organizational objectives,
network administrators define policies for network devices.
• Requirements of network policies –
1. Establish a clear communication
2. Defines the scopes
3. Enforceable by law
4. Sufficient Guidance
Policies of Network Security

• Types of Network Policies
1. Data Policy – a data security policy addresses such topics
as data encryption, password protection and access control which deals
to prevent the data from unauthorized access.
2. Email Policy– mail security is a term for describing different procedures
and techniques for protecting email accounts, content, and communication
against unauthorized access, loss or compromise. Email is often used to
spread malware, spam and phishing attacks.

3. Disaster Recovery/Incident Response policy - All networks might have a
disaster. This could range from the entire building holding a network
burning down to flood damage to malicious damage by a hacker or
disgruntled employee. When a disaster happens, an organization needs to
get the network back up and running as quickly as possible or it might go
out of business.
4. System Management policy – it means that there should be some system
administrators and employees are must present in an organization to
prevent the networks and system.

Thank You
The Avi Sharma
Cyber Security Expert

Networking fundamentals

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