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Which protocol do you speak? (Part II)

In part 1, we took a look at TCP/IP & DNS. Those are just some of the most important protocols that are necessary for the Internet to function the way it does. Consider them the road network that allows traffic to get from one place to another. Let’s now take a closer look at some of the traffic that uses this road network.

Perhaps the most pervasive activity to take place on the Internet is web browsing, or what was previously referred to as the World Wide Web (WWW). This is really just a fancy name for information stored on one computer being made available to multiple other computers elsewhere on the network. The computer that holds the information uses what’s called aWeb Server to make that information available. There are different types of web server but a couple of the most commonly used are the Apache server (which typically runs on Linux servers) and the IIS server (which runs on Microsoft Windows servers). The web browser doesn’t care which type of web server is being used to serve the content and neither does the end user – you. To access the information, the receiving computer uses what’s called a web browser. Common web browsers are Microsoft Internet Explorer (IE), Mozilla Firefox, Google Chrome, Apple Safari, Opera and others. In theory, it shouldn’t matter which browser is used to access content on a web server. In practice, however, different web browsers can render webs page slightly differently to each other. Different web browsers have different features and it can very much be down to personal preference as to which one a user wishes to use. Some web browsers only work on certain operating systems.

 

The web browser and the web server use a protocol called HyperText Transfer Protocol (HTTP) to communicate with each other. When you type in the name of a web page or click a link on an existing web page, the content of the page is being delivered from the web server to the web browser using the HTTP protocol. This traffic is sent in an unencrypted form between the server and browser. This means that if someone is ‘sniffing’ the network, the content of that web page can be seen as it moves between the server and the browser. That’s perfectly fine if all you are looking at is images and text that’s freely available but if you need to type in a password, or perhaps you are buying something and need to type in your credit card details, then this becomes a problem, as you don’t want anyone to be able to read your personal details as they travel between your web browser and the remote web server. The remote web server could be on the other side of the world and there are lots of places in between where someone could be listening in. To solve this problem, there is a secure version of the HTTP protocol called HTTPS. When a web server and web browser agree to use the HTTPS protocol, all traffic that is sent between them is first encrypted. That way, if someone ‘sniffs’ the network to intercept the data, they won’t be able to read or understand any of it.

 

The address of a web page is called a Uniform Resource Locator (URL). When you look at the URL, in your web browser, the first few letters will identify what type of protocol is being used to exchange information with the remote web server. For web pages, this will typically be either http or https – depending on whether the connection is encrypted or not. Sometimes, a web site address (URL) may start out using http but then switch to https. This typically happens on a shopping web-site, where going to your shopping cart and making payment is where the switch to https happens. If you ever need to enter personal details into a web page, it’s always a good idea to make sure that the connection is secure and that you are using the HTTPS protocol at the time. Different web browsers indicate this in different ways, such as displaying a locked padlock icon, for example..