Mateusz Lewczak explains how the AFD.sys driver works under the hood on Windows 11. In Part 1 [1], he demonstrates how to use WinDbg and the NtCreateFile call to manually craft a raw TCP socket, bypassing the Winsock layer entirely.

Part 2 of the series [2] dives into the bind and connect operations implemented via AFD.sys IOCTLs. Mateusz shows how to intercept and analyze IRP packets, then reconstruct the buffer needed to perform the three‑way TCP handshake by hand in kernel mode.

[1] https://leftarcode.com/posts/afd-reverse-engineering-part1/ [2] https://leftarcode.com/posts/afd-reverse-engineering-part2/