Welcome to Scapy, the Python library that is designed to manipulate, send, and read packets. Scapy is one of those tools that have a large amount of applicability, but it can seem complex to use. Before we set off, there are some basic rules to understand about Scapy that will make creating scripts much easier.

Firstly, refer to the previous sections to understand the TCP flags and how they are represented in Scapy. You will need to look at the flags mentioned earlier and their relevant positions to use them. Secondly, when Scapy receives responses for a packet sent, the flags are represented by binary bits in octal format within the 13th octet of a TCP header. So, you have to read the response based on this information.

Look at the following table, which represents the binary positional values of each flag as it is set:

So when you are reading the responses from the TCP packets and looking for a specific type of flag, you have to do the math. The preceding table...