Capstone ProjectAdvanced

Create a Network Protocol Stack

Build a complete TCP/IP implementation in userspace using raw sockets (AF_PACKET on Linux). Implement Ethernet frame handling, ARP for address resolution, IPv4 with fragmentation, ICMP echo, and TCP with the full state machine including slow start, congestion avoidance, and retransmission. Top it off with a simple HTTP/1.1 server.

6-8 weeks 5 milestones 20 build steps, 18 linked tasks

The whole plan below is free to read: every milestone, its build steps, how to verify it, and which tasks and visualizations to use. Tracking your progress, the completion certificate and the graded tasks it links to need a plan.

Related Tracks

NetworkingStorage & Databases

Prerequisites

C Programming Deep Dive

Milestones

Each milestone opens into the build order, a way to check your work, the tasks that drill its pieces, and the visualizations that show the machinery. Work top to bottom.

Another host on the network can resolve your address.

Build it in this order

1Open a raw socket (AF_PACKET on Linux) or a TUN/TAP device, and dump the frames you receive as hex.
2Parse the Ethernet header: destination, source and EtherType, then dispatch on EtherType.
3Answer ARP requests for your address and send your own, keeping a cache with an expiry.
4Build frames as well as parse them, checking your output against tcpdump before you trust it.

How you know it works

ip neigh on another host shows your MAC for your IP after your stack answers a request, and tcpdump reports no malformed frames.

Practise the pieces first

Parse an Ethernet Frame Manually Implement an ARP Request using Raw Sockets Capture All Traffic in Promiscuous Mode Capture Packets with libpcap

See how it works

Packet encapsulation

Build it in your own repo

There is no upload step. You build this on your own machine, in your own repository, and tick each milestone off here as it works. Finish all 5 and you get a certificate with a verification id; connect GitHub first and a gist artifact is created alongside it.

Start with the first task Browse the prerequisite tracks