History of Linux and FOSS

 History of Linux

For the history of Linux, it is best to understand more about Unix. Unix was made in 1969 by Bell Labs by Ken Thompson and Dennis Ritchie. It was intended to be a multi-user system and was rewritten with C in 1973 for portability. Unix was released to the public by Bell Labs with Version 6 in 1975 for general use. 

In 1983, Robert Stallman created the GNU Project to create a free Unix- like system which is something that Linux eventually evolved from. Linus Torvalds started Linux as a personal hobby project back in 1991. This was a similar model to the GNU Project and was licensed under the GNU General Public License.

In 1992, the GNU Project and the Linux Kernel were merged under the GNU GPL which allowed for an open-source version of Linux. There are different distributions that came out like Debian and Slackware in 1993 allowing for more distributions and flavors later on. There are three main distributions today that most Linux systems are derived from. They include Debian, Red Hat and Arch Linux mainly, which are where the different flavors originate from.

History of FOSS

FOSS is something that grew out of the general cooperation of building software in the 1960’s and 1970’s. It was built on the concept of free software which Robert Stallman’s GNU Project and Free Software Foundation helped with the development of Free and Open-Source Software later on using Linux and other distributions. The Free Software Foundation was made in 1985 by Robert Stallman.

In 1998, the term open-source was coined by the Open-Source Initiative which helped the development of different companies and organizations contributing to other open-source projects in the corporate world. This is something that is happening still today. Linux is used heavily in web servers, cloud computing and in mobile devices like Android.

Knowledge Byte

The history of Linux is something that I have studied for in college and also when studying for the LPI Linux Essentials certification that I have. There are some ways to study for the Linux Essentials which include a study plan, having three or more resources and also keeping a schedule of each section that you have selected for your study sessions. It is also good practice to eat healthier and get enough sleep, so you are not having issues with energy or your mental health.

Conclusion

These are some of the events that contributed to Linux and FOSS. There are companies that continue to contribute to open-source projects like Git and Apache Server. The development of more distributions and flavors is getting Linux to be a more portable operating system than Windows. Linux is now used to power corporate systems and supercomputers along with embedded systems.

OSI Model vs. TCP/IP Model

 The OSI Model (Open Systems Interconnection) is essentially a reference model that helps IT technicians understand the different layers. For the TCP/IP Model, this is the Transmission Control Protocol/ Internet Protocol that is a functional model and is how the layers actually work. There are seven OSI layers compared to the four TCP/IP layers. The OSI model was made by the International Organization for Standardization as a conceptual model.

OSI Model

The best way to think about the OSI Model is to break it down into layers. These are from the bottom to the top and starts with layer 1 which is the Physical layer, layer two is the Data Link layer, the Network layer, Transport layer, Session, Presentation and layer 7 which is the Application layer. By using the Please Do Not Throw Sausage Pizza Away mnemonic you can remember these layers.

The Physical layer is the actual hardware, cabling, and wireless mediums and uses encapsulation to go to the Data Link layer which are frames. The Network layer uses packets and encapsulates the frames into packets. By the fourth layer, the Transport layer, the packets are encapsulated by ports.

With the Session layer, the ports are encapsulated by sessions which interact with layer six to allow for encryption and then the Application layer which is by that point data. By understanding these layers, you can understand more about what the TCP/IP Model is about and why it is easier to troubleshoot with the OSI model. The OSI model is also used by vendors that create hardware and software to be interoperable.

TCP/IP Model

In the TCP/IP Model there are four layers which are the Network Access layer that corresponds to Layer 1 and 2 of the OSI Model, the Internet layer for Layer 3, Transport layer for layer 4, and the Application layer which corresponds with layers 5, 6, and 7 of the OSI Model. This model was developed by the Department of Defense and is a practical standard for internet communications.

Conclusion

By learning more about the OSI and TCP/IP models you can understand how to troubleshoot more effectively. There are some encapsulation and decapsulation items going up and down the TCP/IP stack at the same time. This allows for effective communication across systems. When you understand this at a deeper level you can go for more advanced certifications like the CCNP or even the CCNA.

NAT Types

 Network Address Translation

There are three different types of NAT which are Static NAT, Dynamic NAT, and also Port-Address Translation which is also known as NAT Overload. Static NAT is a one-to-one mapping of an internal private address into a public address. These types of NAT are some of the main types and there are some others like gaming types of NAT that I will not go over in this blog post.

Dynamic NAT is a one-to-many mapping with one private address and many public addresses. The Port Address Translation is used with a single public address and multiple private addresses. PAT, also known as NAT overload, is used mostly by home routers and is the most common type. PAT is done using port numbers for each session that is connected by each IP address.

Static and Dynamic NAT

The static NAT type is used mostly by people hosting a server in a private network behind a firewall or router. The dynamic NAT type of Network Address Translation is used by companies to map their IP addresses. This results in a one private IP to multiple public IP addresses. This is most commonly done by companies with larger networks.

Knowledge Byte

There are some things to work on regarding computer networking certifications. The certifications that this will help with the most are the CCST Networking and the Network+ certification. Certification study is one of the best things that you can do for your career and will help you get better jobs over time along with some education.

In order to understand a book or course you would want to section off the information in a study plan and be consistent in order to finish the study plan before taking one of these exams. With a study plan there is built in consistency, and you will want to keep pace with your study sessions. This is in order to pass the exam or class that you are in. If you stick to your plan, you can make it better or do better things with it next time.

Conclusion

These types of NAT are the main types and will help you out on exam day if you can put in a solid study plan along with some reading. I do have the CCST Networking and the CCNA along with other certifications and this information has helped me with those exams. When working on a study plan it should include some reading, practice, and thorough online course study.