Let’s code a TCP/IP stack, 1: Ethernet & ARP

Writing your own TCP/IP stack may seem like a daunting task. Indeed, TCP has accumulated many specifications over its lifetime of more than thirty years. The core specification, however, is seemingly compact1 – the important parts being TCP header parsing, the state machine, congestion control and retransmission timeout computation.

The most common layer 2 and layer 3 protocols, Ethernet and IP respectively, pale in comparison to TCP’s complexity. In this blog series, we will implement a minimal userspace TCP/IP stack for Linux.

The purpose of these posts and the resulting software is purely educational – to learn network and system programming at a deeper level.