Protocol Stack and Addressing

• Team CharMusafirs– Ankan Adhikari [1MS07IS010]– Chandan Kumar [1MS07IS019]– Chandresh Kumar [1MS07IS020]– Pawan Kumar [1MS07IS065]

Overview of the OSI model

OSI Model

Application Layer

1. Application layer interacts with application programs and is the highest level of OSI model.

2. Application layer contains management functions to support distributed applications.

3. Application layer functions typically include identifying communication partners, determining resource availability, and synchronizing communication.

4. Examples of application layer are applications such as file transfer, electronic mail, remote login etc.

OSI Model

4

Application layer Protocols

DHCP [Dynamic Host Configuration protocol]

• Provides static/dynamic address allocation, both manual and automatic.

• Dynamic : Assigns IP address for a specified time (lease time)• Needed when a host moves from network to network or is

connected/disconnected from a network.• DHCP server keeps a table of past IP address assignments, so

that it can preferentially assign to a client the same IP address that the client previously had.

OSI Model

PRESENTATION LAYER

• The presentation layer ensures that the information that the application layer of one system sends out is readable by the application layer of another system.

• If necessary, the presentation layer translates between multiple data formats by using a common format.

• Provides encryption and compression of data.

• Examples :- JPEG, MPEG, ASCII, EBCDIC, HTML , AFP, ICA, LPP,NCP, NDR,RDP,XDR,X.25 PAD.

OSI Model

OSI Model

PRESENTATION LAYER PROTOCOL

ASCII (American Standard Code for Information Interchange )• ASCII is a character-encoding scheme based on the ordering of the English alphabet. ASCII

codes represent text in computers, communications equipment, and other devices that use text.

• ASCII includes definitions for 128 characters: 33 are non-printing control characters that affect how text and space is processed; 94 are printable characters, and the spaces is considered an invisible graphic.

HTML (Hyper Text Markup Language)

• HTML is the predominant markup language for web pages. It provides a means to create structure documents by denoting structural semantics for text such as headings, paragraphs, lists etc as well as for links, quotes, and other items.

• It allows images and objects to be embedded and can be used to create interactive forms.

SESSION LAYER

• The session layer defines how to start, control and end conversations (called sessions) between applications.

• This includes the control and management of multiple bi-directional messages using dialogue control.

• It also synchronizes dialogue between two hosts' presentation layers and manages their data exchange.

• The session layer offers provisions for efficient data transfer.

• Examples :- SQL, ASP, ADSP,ASP,.ISO-SP, OSI, L2F, L2TP, NetBIOS

OSI Model

OSI Model

SESSION LAYER PROTOCOL

SSH (Secure Shell)• SSH is a protocol for creating a secure connection between two systems.• In the SSH protocol, the client machine initiates a connection with a server

machine.• SSH uses public-key cryptography to authenticate the remote computer and allow

the remote computer to authenticate the user, if necessary.

9

OSI and Protocol StackOSI: Open Systems Interconnect

OSI Model TCP/IP Hierarchy Protocols

7th

Application Layer

6th

Presentation Layer

5th

Session Layer

4th

Transport Layer

3rd

Network Layer

2nd

Link Layer

1st

Physical Layer

Application Layer

Transport Layer

Network Layer

Link Layer

Link Layer : includes device driver and network interface cardNetwork Layer : handles the movement of packets, i.e. RoutingTransport Layer : provides a reliable flow of data between two hostsApplication Layer : handles the details of the particular application

MAC Spoofing

1. Emulating MACs for illegal access.2. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\

Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318} contains driver information.

3. DriverDesc contains the Adapter’s information, Adding a NetworkAddress key.

4. 3rd party tools: MadMACs, MacMakeUp.5. Loosely possible to DDoS.

OSI Model