Source: Freepik
Welcome to the third and final part of our blog series on firewalls! In the first post we looked at the role of firewalls, and in the second we looked at the types of firewalls. In this post, we take a look at the OSI model (Open Systems Interconnection Model) and the different levels at which firewalls can operate.
What Is the OSI Model?
The OSI model (Open Systems Interconnection Model) is a theoretical concept that divides the structure of a communication system into seven layers. These layers are used to standardise and organise communication between different devices and systems in a network. The model is used in various areas of computer network technology, including network architecture design, network protocol development, network diagnostics and troubleshooting, network management and other components.
The model was developed by the International Organisation for Standardisation (ISO) and is an important framework for network architecture and communication. In relation to the OSI model, a firewall can work on different levels.
The Seven Layers of the OSI Model:
- Physical layer (Layer 1): This layer deals with the transmission of raw data via physical media such as cables, radio waves or optical fibres. It defines the electrical, mechanical and functional specifications for the physical connection between the devices.
- Security layer (layer 2): This layer is responsible for reliable data transmission between neighbouring network elements. It deals with error detection and correction as well as addressing and access to the medium.
- Network layer (layer 3): The network layer is responsible for forwarding data packets from one network to another. It enables route determination and the routing of data through different networks.
- Transport layer (layer 4): This layer provides end-to-end communication and control over the flow of data. It is responsible for segmentation, flow control and error recovery.
- Session layer (Layer 5): The session layer establishes, manages and terminates sessions between applications. It enables the exchange of data between applications on different devices.
- Presentation layer (layer 6): This layer takes care of data representation and formatting to ensure that data can be understood by an application, regardless of differences in internal data representation.
- Application layer (layer 7): The application layer is the top layer of the OSI model and comprises the applications themselves that interact with the network. It provides services for the user applications, such as e-mail, web browsers and file transfer.
Significance of the OSI Model
The OSI model serves as a reference point for the development and implementation of network protocols and technologies and facilitates interoperability between different systems and manufacturers. This means that the basis is created so that different systems, products or services can interact, communicate and work together, even if they come from different manufacturers, use different technologies or are operated in different environments. This is important so that these systems can communicate effectively with each other, exchange data and pursue common goals without the need for extensive customisation or special interfaces.
In addition, the OSI model provides a clear structure for analysing and troubleshooting network problems by dividing the various aspects of communication into defined layers. A firewall can therefore work on the different layers of the OSI model to protect networks and regulate data traffic. To ensure adequate protection, different types of firewalls can be used depending on the requirements and complexity of the network.
Firewalls are critical to the security and integrity of networks, and a deep understanding of how they work is essential. Hopefully we’ve given you an insight into firewalls and how you can protect yourself.
Responsible for the content of this article are Malak Mostafa and Morgane Overath.
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