Complete Lab 4 submission

[rslwqr]

Lab 4 — OS & Networking

Completed all required tasks and the bonus.

Task 1

• Captured a complete POST /notes request with tcpdump
• Identified the TCP three-way handshake, HTTP request/response, and TCP connection close
• Added the decoded trace to lab4-trace.txt
• Performed listener, routing, reachability, DNS, and service-log checks
• Documented macOS equivalents for Linux-specific commands
• Added a 502 debugging approach

Task 2

• Reproduced the bind: address already in use deployment failure
• Diagnosed the issue using an outside-in debugging chain
• Checked the process, listening socket, health endpoint, firewall, and name resolution
• Repaired the deployment and verified /health
• Added a blameless mini-postmortem with prevention measures

Bonus

• Configured Caddy as an HTTPS reverse proxy
• Captured the TLS handshake on port 8443
• Analyzed ClientHello and ServerHello in Wireshark
• Documented TLS version, cipher suite, SNI, and key share
• Inspected the Caddy certificate chain with OpenSSL
• Explained how deprecated TLS 1.0/1.1 versions are excluded during negotiation

Artifacts

• submissions/lab4.md
• lab4-trace.txt
• lab4-tls.pcap
• Caddyfile
• ClientHello and ServerHello Wireshark screenshots