WNS Unit-02

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1)Describe the process of establishing a secure SSH connection for terminal access and file transfer over wireless networks.

Connect TCP to SSH server:

SSH command is connected to the server over the internet by using port 22.

SSH Handshake:

When the connection starts, the client & server exchange public keys, i.e. it performs an SSH handshake.

Prevent Man-in-the-Middle Attack:

SSH client checks the server's identity to prevent the Man-in-the-Middle Attack.

Authentication:

Once the secure connection is finished, the client logs in to the servers.
There are two methods:

a) Password Authentication
b) Public-Key Authentication

Public-Key authentication is more secure when compared to password authentication.

Secure command-line shell:

After logging in, the user gets access to a secure command-line shell.
Here, attackers cannot easily launch an attack on a system.

SCP and SFTP:

SCP and SFTP are the tools used to transfer files safely.

WNS Unit-02

2) Importance of SSH Protocol:

1) Replacing Insecure Protocols:

The Insecure Protocols transmit the data in plain text, which makes attackers easily launch attacks on the system.
The SSH Protocol was developed to replace these Insecure Protocols.

2) Replacing Insecure File Transfer Protocol:

The SSH Protocol was developed to replace the Insecure File Transfer Protocols.
It ensures Encryption and Authentication during File Transfer.

3) Encryption:

The process of transmitting the data from plaintext to ciphertext is called Encryption.
SSH protocol provides strong Encryption.

4) Authentication:

Authentication is used to verify the identity of a user or device.
There are mainly two types of Authentication:

a) Peer-Entity Authentication
b) Data-Origin Authentication

SSH Protocol provides strong Authentication.

5) Security:

SSH Protocol provides security and prevents common attacks like:

DNS spoofing
IP spoofing
Man In The Middle Attack

WNS Unit-02

3) IPsec, SSL, TLS

Protocol	Description
IPsec	IPsec stands for Internet Protocol Security IPsec is in the Network Layer (Layer-3) IPsec is very complex IPsec may cause overhead IPsec works with IP Protocols IPsec uses X.509 certificate
SSL	SSL stands for Secure Socket Layer SSL lies between the Transport Layer (Layer-4) and the Application Layer (Layer-1) SSL is very simple SSL has lower overhead SSL works with TCP Protocols SSL uses X.509 certificate, where the client side is optional
TLS	TLS stands for Transport Layer Security TLS is in the Transport Layer (Layer-4) TLS is very simple TLS has lower overhead TLS works only with TCP Protocols TLS uses X.509 certificate, where the client side is optional

WNS Unit-02

4) Architecture of IPsec:

IPsec uses two protocols. They are:

a) ESP Protocol
b) AH Protocol

a) ESP Protocol:

ESP stands for Encapsulating Security Payload
ESP Protocol uses an Encryption Algorithm and may also use an Authentication Algorithm

b) AH Protocol:

AH stands for Authentication Header
AH Protocol do not use an Encryption Algorithm and uses an Authentication Algorithm to verify the identity of a user or device

Encryption Algorithm:

The Process of transmitting the data from plaintext to ciphertext by using a cryptographic Algorithm is called as Encryption Algorithm
Encryption Algorithm is used to encrypt the data

Authentication Algorithm:

The Process of verifying the identity of a user or device is called as Authentication Algorithm
Authentication Algorithm is used to authenticate the data

DOI:

DOI stands for Domain of Interpretation
DOI is an identifier that supports both ESP Protocol and AH Protocol

Key Management:

Key Management describes how the keys are exchanged between the sender and the receiver

WNS Unit-02

5) Wireless Transport Layer Security (WTLS):

WTLS stands for Wireless Transport Layer Security
WTLS is a security Protocol specially designed for the Wireless Application Protocol (WAP)
WTLS provides:
- Data Integrity
- Authentication
- Encryption

SSL/TLS vs WTLS:

SSL/TLS uses the TCP Protocol, which provides connection-oriented services
WTLS uses the UDP Protocol, which provides connectionless services

Operations of WTLS:

Handshake process:

The Client initiates the handshake with the Server via WAP Gateway
There are three classes:
- WTLS class 1 - No certificates are used
- WTLS class 2 - Only Server Certificates are used
- WTLS class 3 - Both Client and Server certificates are used

Encryption Algorithm:

The Process of transmitting the data from plaintext to ciphertext by using a cryptographic Algorithm is called as Encryption Algorithm
Encryption Algorithm is used to encrypt the data

Authentication Algorithm:

The Process of verifying the identity of a user or device is called as Authentication Algorithm
Authentication Algorithm is used to authenticate the data

Key Management:

Key Management describes how the keys are exchanged between the sender and the receiver

WNS Unit-02

6) OSI Layer:

OSI stands for Open System Interconnection

The OSI Model consists of 7 Layers:

Physical Layer
Data Link Layer
Network Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer

i) Physical Layer:

Physical Layer is Layer 1 in the OSI Model
It is responsible for the physical connection between the devices.

ii) Data Link Layer:

Data Link Layer is Layer 2 in the OSI Model
It is responsible for the node-to-node transmission of data

iii) Network Layer:

Network Layer is Layer 3 in the OSI Model
It is responsible for the host-to-host transmission of data

iv) Transport Layer:

Transport Layer is Layer 4 in the OSI Model
It is responsible for the end-to-end transmission of data

v) Session Layer:

Session Layer is Layer 5 in the OSI Model
It is responsible for establishing, managing and terminating the sessions

vi) Presentation Layer:

Presentation Layer is Layer 6 in the OSI Model
Presentation Layer is also called as Transition Layer

vii) Application Layer:

Application Layer is Layer 7 in the OSI Model
Application creates the data

WNS Unit-02

7) Data Link Layer:

Data Link Layer is Layer 2 in the OSI Model
It is responsible for the node-to-node transmission of data
The Data Link Layer is divided into two sub-layers:
- a) Logical Link Control (LLC)
- b) Media Access Control (MAC)

a) Logical Link Control (LLC):

LLC stands for Logical Link Control
Logical Link Control is the upper part of the Data Link Layer
Functions of LLC:
- i) Frame Synchronization:
  - LLC manages the Frame Structure and provides proper synchronization between sender and receiver
- ii) Connection Management:
  - Responsible for establishing the connection between devices
- iii) Flow Control:
  - It stops the sender, who is sending data quickly
  - It ensures that the receiver does not get more data
- iv) Error Control:
  - Error control detects and corrects the errors
  - Types of Errors:
    - Single-bit error
    - Burst error

b) Media Access Control (MAC):

MAC stands for Media Access Control
Media Access Control is the lower part of the Data Link Layer
Functions of MAC:
- i) Frame Detection:
  - Frame Detection defines the frame boundaries
- ii) Physical Addressing:
  - Adds the Source and Destination MAC addresses to the frames
- iii) Access Control:
  - It prevents collisions when multiple devices send data at the same time
  - Example:
    - CSMA/CD
    - CSMA/CA
- iv) Error Checking:
  - It checks the errors by using CRC
  - CRC stands for Cyclic Redundancy Check

WNS Unit-02

8) Connection-Oriented Service VS Connectionless Service

Data Link Layer and Transport Layer can provide communication in two modes:

i) Connection-Oriented Service
ii) Connectionless Service

Connection-Oriented Service	Connectionless Service
Connection is required between sender and receiver before the data transmission	Connection is not required between sender and receiver before the data transmission
Packets follow the same route	Packets do not follow the same route
Feasible and reliable	Not feasible and unreliable
Less scalable and high overhead	Highly scalable and low overhead
Handles errors	Does not handle errors
Example: TCP (Transmission Control Protocol)	Example: UDP (User Datagram Protocol)

9)Cryptographic Framework:

i) Authentication:

The Process of verifying the identity of user or device is called as Authentication
Authentication Algorithm is used to authenticate the data
Types of Authentication:

There are mainly two types of Authentication:

a) Peer Entity Authentication
b) Data-Origin Authentication

ii) Confidentiality:

Confidentiality ensures that hiding the information from unauthorized access during exchange

iii) Data Integrity:

Data Integrity prevents the unauthorized modifications to the Information
Data Integrity also detects the modification made

iv) Non-Repudiation:

Non-Repudiation prevents the denial of message transmission between Sender and Receiver

Framework Structure for IoT Security:

i) Device-Level Security:

IoT devices use symmetric key cryptography for fast and lightweight encryption.
Symmetric key cryptography like:

AES Algorithm
DES Algorithm

ii) Network Level Security:

IoT devices use secure protocols to protect data during wireless transmission.
Secure protocols like:

SSL/TLS
WTSL
IPsec

iii) Application Level Security:

It encrypts application data and ensures secure API access.

10) Unicast Key and Multicast Key:

i) Unicast Key:

An encryption key used between one transmitter and one receiver
It secures the communication between two devices
Unicast Key is very simple because only two devices manage the key
Valid only during the session
Example:

Laptop connecting to a WiFi Network

ii) Multicast Key:

An encryption key used between one transmitter and multiple receivers
It secures the group communication like broadcasts, video streaming
Multicast Key is very complex because the key is shared across multiple devices
Valid as long as group is changed
Example:

Manager sharing his presentation to all his employees