In this section, we'll take a look at the BPF, its syntax, and some of its history.
So, let's talk about BPF's history. Many years ago, every operating system had its own packet filtering API. There are a number of examples, such as Sun, DEC, SGI, and Xerox. They all had their own operating systems, and each operating system had its own API for capturing and filtering packets. So, when you needed to do network analysis, you had to use their specific software, which is built into the operating system, and their specific filtering capabilities within the API that they designed. That made it very difficult because depending on the implementation of your network and what different operating systems were involved, you had to know all these different APIs and all of these different filtering rules in order to get anything done. So, in 1993, Steven McCanne and Van Jacobson released a paper titled The BSD Packet Filter (BPF) and they outlined the rules and the...