gw-01 — References

Protocol specs

• RFC 9293 — Transmission Control Protocol (the consolidated TCP spec; supersedes 793). The state machine and the handshake.
• RFC 768 — User Datagram Protocol. Short enough to read in full.
• RFC 7413 — TCP Fast Open (handshake-latency optimization).
• HAProxy PROXY protocol — v1 (text) and v2 (binary) spec. https://www.haproxy.org/download/2.8/doc/proxy-protocol.txt

The C10K lineage

• Dan Kegel, The C10K problem — the original statement of why thread-per-connection doesn't scale. http://www.kegel.com/c10k.html
• Zuul 2: The Netflix Journey to Asynchronous, Non-Blocking Systems — the production answer at Netflix; event loop vs thread-per-request. https://netflixtechblog.com/zuul-2-the-netflix-journey-to-asynchronous-non-blocking-systems-45947377fb5c
• Netty docs / Netty in Action — the event-loop framework behind Zuul and Pushy. https://netty.io/

Kernel & performance

• Brendan Gregg, Systems Performance (2nd ed.) — the network stack, the USE method, epoll/kqueue, tcpdump/ss/bpftrace.
• man 7 tcp, man 7 socket, man 2 epoll, man 2 splice, man 2 accept4 — read these directly; they are the spec for the code.
• Cloudflare blog — The curious case of TIME_WAIT, SYN packet handling in the wild, How to stop running out of ephemeral ports. https://blog.cloudflare.com/
• Marc Brooker — It's About Time and the timeouts/retries series for why connection-level timeouts must be bounded. https://brooker.co.za/blog/

Tooling to learn alongside

• ss -lnti / ss -s — listening-socket accept-queue depth, per-socket TCP info, summary counters.
• netstat -s / nstat — kernel TCP counters (listen overflows, SYN drops, retransmits).
• tcpdump / Wireshark — see the handshake and FIN/RST on the wire.
• iperf3, wrk, wrk2, vegeta — load generators for the steps.
• bpftrace / bcc — trace accept-queue overflows and retransmits.

Cross-lab dependencies

• Upstream: db-01 (syscalls, page cache) for the I/O intuition.
• Downstream: gw-02 (terminate the stream), gw-03 (filter chain on top of the acceptor), gw-04 (pool the connections this lab opens), gw-05 (drain millions of them), gw-09 (where the packets actually flow in Kubernetes).