TCP analysis I

In this section, we'll take a look at how TCP works, what's in the TCP header, and some of the flags and options.

If you'd like to learn more about TCP, you can look at the RFC that's available from the IETF at https://tools.ietf.org/html/rfc793:

You're looking for RFC: 793 for TCP, which is the original specification for TCP.

In the preceding screenshot, you can see different sections within IETF, which provide a little bit of interactivity. You can click on the different RFCs that have updated the TCP specifications; if you scroll down, it also provides you a nice little table of contents. The RFC shows a little diagram of what the TCP header looks like:

We have Source Port; Destination Port; Sequence Number; Acknowledgment Number; Data Offset; some Reserved bits; Window size; header Checksum; an Urgent Pointer; and Options, which is an expandable section. We have some Padding and then the actual data.

Go into Wireshark and let's go to a TCP packet. We can see we have some TLS...