Johnny Li Portfolio

Network engineering / infrastructure / automation

Networks, systems, and infrastructure built to be understood

Network engineer based in California, building tools for routing, protocol analysis, diagnostics, and infrastructure automation after nearly three years in hands-on systems support at UC Santa Cruz.

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Selected engineering work

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Network systems / causal debugging

HOPSCOTCH

An interactive network-systems laboratory built around one deterministic model of packet bytes, protocol state, routing, policy, failures, captured PCAP/PCAPNG evidence, and end-to-end application behavior.

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Diagnostics / cross-platform systems

Network Diagnostics Suite

A privacy-first measurement suite with a browser client, a React + TypeScript desktop workbench hosted by Photino.NET, and a .NET CLI for throughput, latency, loss, DNS, routing, MTU, TLS/HTTP/3, interface, Wi-Fi, and LAN diagnostics.

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OSPF / failure testing

OSPF Resiliency Lab

A four-router FRRouting lab that proves equal-cost paths, injects a silent core failure, measures reconvergence, verifies reachability, and preserves machine-readable recovery evidence.

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Python / network automation

Network Config Auditor

A dependency-free Python CLI that parses Cisco IOS-style configurations and reports security, management, switching, and routing issues with severity, source-line evidence, and remediation guidance.

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C++ / transport protocols

Reliable Transport over UDP

A sliding-window file-transfer protocol with per-packet acknowledgements, timeout-based retransmission, deliberate DATA and ACK loss, out-of-order reassembly, and structured packet evidence.

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C++ / HTTP / TLS

Concurrent Clear-to-Secure Proxy

A concurrent forward proxy that accepts clear-text HTTP, establishes verified TLS upstream, enforces reloadable hostname and IP policy, preserves response framing, and records structured access logs.

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Experience

Production support experience underneath the networking and systems work.

Apr 2023 — Mar 2026

IT Technician

UC Santa Cruz · Humanities Division

Managed support work from intake through resolution in ServiceNow across hardware, software, accounts, applications, and connectivity. Handled device deployment and migration, Jamf-supported Apple workflows, Apple GSX repairs, inventory, documentation, audiovisual support, and technician mentoring; also supported research-technology work in containerized Nautilus computing environments.

2022

Technical & E-commerce Intern

Accuzone Inc.

Worked between customers and technical teams, translated product information, and maintained website and marketplace content with search visibility in mind.

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About

I like systems where evidence, state, and failure can be inspected instead of guessed.

I started in hands-on support and moved deeper into networking, protocol behavior, and infrastructure tooling. The projects here emphasize deterministic behavior, measurement, reproducible failure cases, and explanations grounded in observable evidence.

Education

University of California, Santa Cruz

B.A. in Network and Digital Technology · 2026

Technical focus

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Networking & protocols

  • IPv4/IPv6, TCP, UDP, DNS, DHCP, ARP/ND, VLANs, STP/RSTP, NAT, and ACLs
  • OSPF/OSPFv3, BGP, ECMP, RIB/FIB behavior, route policy, and reconvergence analysis
  • HTTP/1.1, HTTP/2, HTTP/3, QUIC, TLS, socket programming, and forward proxies
  • Cisco IOS, FRRouting, Containerlab, Wireshark, traceroute, path MTU, latency, jitter, and loss analysis

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Automation & systems development

  • Python, Bash, SQL, C/C++, C#/.NET, JavaScript, and TypeScript
  • React, Vite, Node.js, Photino.NET, and Cloudflare Workers
  • Deterministic state models, versioned contracts, structured evidence, and cross-platform tooling
  • Git, GitHub Actions, CI/CD, automated testing, static analysis, accessibility, and performance validation

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Platforms & operations

  • Docker, Kubernetes, Podman, Cloudflare, Linux, Windows, and macOS
  • ServiceNow, Jamf, Apple GSX, Google Workspace, and Microsoft 365
  • Device deployment, migration, repair, inventory, documentation, and research-computing workflows
More skills Fewer skills

Protocol internals & network analysis

  • HTTP message framing, concurrent network applications, DNS/TCP/TLS phase timing, and endpoint selection
  • Route/default-route, interface, Wi-Fi signal/channel/band, LAN throughput, and network metadata analysis
  • Packet capture parsing, byte-to-field lineage, retransmission/overlap handling, and evidence-bounded inference
  • Traffic policy, queueing, congestion response, failure injection, and causal troubleshooting models

Tooling & validation

  • Playwright, Vitest, CodeQL, schema/parity fixtures, and compatibility suites
  • Unit, integration, browser, end-to-end, visual-regression, and accessibility testing
  • Performance budgets covering bundle, DOM, heap, and representative high-density workloads
  • Cloudflare Workers/Static Assets, GitHub Pages, deployment smoke testing, and release packaging

Systems & endpoint operations

  • Windows and macOS administration; Linux systems and command-line workflows
  • Hardware diagnostics and repair; endpoint inventory and lifecycle management
  • Application deployment, migration, Apple provisioning/support, and user-facing documentation
  • Nautilus research-computing environments using Docker/Podman and Kubernetes-backed infrastructure
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Contact

Let’s talk.

I’m open to network engineering, infrastructure, systems, and technical application roles—and willing to relocate for the right work.