TCP/IP Part 1

This is a new series of blog posts on TCP/IP which is transmission control protocol internet protocol and is based on the Learning TCP/IP course by Infinite Skills which I am doing. I will be doing a post on a daily basis. TCP/IP is a suite of internet protocols which are basically rules for how computers and their networks communicate over the internet. There are other protocols as well as TCP/IP such as IPX & Appletalk but TCP/IP is the most widely used. The origins of the internet started with the ARPANET the basic backbone of which was constructed in 1967 and was a network for the Department Of Defense in America and was built in a decentralized way to survive a nuclear attack. There were other networks built soon after and around that time in particular networks for universities and scientists to communicate with one another. Initially there was TCP which was a protocol for networks and the IP part came later. This course looks quite a bit at wireshark which is a wireless packet capture and analysis program. It's free to download and contains a filter to look at certain packets of a particular type. The filter box goes red to show it's incomplete and turns green when you enter a complete search. You can right click on a packet and choose an option to search for packets of the same type. In the filter box you enter the equals sign twice to specify a search criteria because there is always the chance the equals sign might be part of the search criteria. You can search for a type of transmission like tcp or ip and ip would cover just about every transmission type so would be useless. There is something called the OSI model which consists of 7 modules which are Physical, Data Link, Network, Transport, Session, Presentation & Application. These modules are called layers and the lowest layer is Physical and the one data from the internet initially comes through & the highest layer is Application which works directly at a software level including your web browser. Data goes from one layer to the next all the way up and down this model. Different types of protocol work with different layers ie HTTP works with Application & TCP works with Transport. There are discrepancies about which protocols work with Session which isn't an exact layer. There is also a TCP model which works similar to the OSI model although the top and bottom module incorporate several layers from the TCP model.