For a customer project, I had to dive into the IPSec protocols at a very low level, and it was a real learning experience for me. I'd been using IPSec to set up network-to-network VPNs for a long time, but had no real idea what was actually going on save for the 30,000 foot view.
So, I tore into it down to the packet level and have written a new Tech Tip covering it. Many, many hours later (including plenty immersed in Adobe Illustrator), I'm happy to share here.
This does not cover the really magic areas such as key exchange, or the details of Security Associations, but it forms the base upon which those topics are built. I plan on a second paper that covers them in the same kind of detail (though I have to learn them first).
