IT • CyberSecurity • Web Dev • DevOps • Dicom/Pacs • RF & Medical Imaging
Home MRI Service & Utilities CyberSecurity Proxy Traefik Docker IT/Server DICOM/PACS APIs javaScript Node.js Python WordPress BASH DevOps RaspBerry_Pi AWS GitHub About(David) Cycling
Cybersecurity

    Cybersecurity

  • Applied security on a live Linux estate
    This site family runs on a hardened multi-site Linux host—not only lab VMs. Focus is practical controls: TLS at the edge, reverse proxies so secrets never sit in the browser, least privilege, logging/bans, and recoverable backups. Classroom theory matters; operating services and briefing stakeholders is where judgment shows up. Confidentiality, integrity, and availability are treated as configuration and process, not slogans.
  • Credentials & education
    AS Cybersecurity — Santa Fe College
  • Institutional posture project — Santa Fe College
    Security posture assessment presented to college leadership (president, board, and other stakeholders). Recommendations stressed actionable near-term items— including centralized visibility (SIEM) and prioritization of lookalike/cousin domains that had long remained available for impersonation—alongside broader hardening themes. Supporting materials:
    View PDF · Download PowerPoint
  • Edge & application protection
    • HTTPS with Let’s Encrypt (TLS at nginx / ISPConfig)
    • NGINX reverse proxies for APIs (keys stay on the server) — Weather, News, Travel
    • Traefik as a Docker routing layer (dashboard + labeled services) — demo UI
    • UFW firewall; fail2ban for intrusion reduction
    • FTPS and mail stack TLS (Postfix and related services where used on the host)
    • Public forms treated as untrusted input so clients cannot freely shape outbound mail content
  • Secrets, access & data
    • SSH key-based authentication and host hardening
    • Secrets in .env and restricted paths (not in the web root)
    • API keys only via server-side proxies
    • Dashboard auth using bcrypt password hashes (htpasswd)
    • MariaDB deployed with secure installation practices; disk quotas where used
    • Portfolio downloads use placeholders only (e.g. env.example)—not production secrets
  • Availability & recovery
    Scheduled host backups with retention, database dumps, and an offsite copy on a separate machine. Backup sets can include configuration and application secrets, so they are treated as sensitive data at rest: access-restricted administrative paths, not published as portfolio files. Restore coverage includes sites, databases, and containerized app stacks under /opt where those jobs are enabled. Encryption of offsite archives is the preferred hardening step when copies leave the host.
    • Cron-scheduled backups with retention/pruning
    • Offsite copy via controlled transfer to a separate machine
    • Documented restore paths for web, DB, and /opt stacks
    • Secrets in backups handled as credentials—not as public downloadable artifacts
Proxy Servers

    Proxy Servers

  • NGINX as web server, reverse proxy & security boundary
    NGINX serves pages efficiently (less RAM, more concurrency than Apache) and acts as a security boundary for APIs: keys stay on the server, not in the client or public files. That lets me publish interactive demos that use personal/limited API accounts without exposing credentials. Reverse proxying at the edge is a core pattern for protecting secrets and controlling outbound API use.
  • Travel — NGINX API proxy
    Travel UI: travel.mriservice.com/travel.html
    JSON endpoint: /api/travel/...
  • Weather — NGINX API proxy
    UI: weather.mriservice.com/weather.html
    JSON endpoint: /api/weather
  • News — NGINX API proxy
    UI: news.mriservice.com/news.html
    JSON endpoint: /api/news
Traefik Proxy
Docker Logo

    Docker

  • docker Server deployments
    Docker deployments provide a convenient light weight way to rapidly spin up and shutdown server deployments in a way to meet demands and balance loads. Samples include high availability/persistent data storage
  • Docker — high availability, persistant data storage
    Dicom/PACS Server
    login: demo - pass: demo123
    WordPress - Spin-up - Debian, MariaDB, Apache
Data Center

    IT/Server

  • Debian Linux NGINX servers
    NGINX v-host serves multiple sites and pages efficiently (less RAM, more concurrency than Apache). Combined with 4 usable static IP address I can effectively serve hundreds of sites from one host.
    • Nginx: HTTPS for websites, normally on port 443.
    • Postfix: SMTP mail delivery and submission.
    • Dovecot: IMAP/POP3 access to mailboxes.
    • Let’s Encrypt: Issues certificates for names such as example.com or mail.example.com.
    • TLS: Uses those certificates to authenticate the server and encrypt network traffic.
  • IT/Server — Security/Hardening, Webservers, Clients & IoT
    • Linux Solutions & Server Deployments
    • Web development
    • Dicom/PACS Servers
    • Embedded/IoT devices
    • RF & wireless optimization/calibration
    • Server Hardening & Security
Sagittal Head MRI Scan

    Dicom/PACS server

  • Live DICOM/PACS server
    Display and review sample diagnostic Radiology Images
  • Sample Radiology Images — MRI & CT images
    server: Dicom/PACS Server
    login: demo - pass: demo123
  • • Server Deployment & Configuration
    • Archive design oriented toward regulated / sensitive imaging workflows (HIPAA-aware practices)
    • Client configuration & maintenance
API Logo

    API Apps

  • API applications
    Interactive demos against third-party APIs. Credentials stay on the server; the browser only calls my endpoints.
  • API — Apps
    Flight Booking App
    Weather App
    News App
javaScript Logo
Node Logo

    Node Js App

  • Production node app deployment
    This MRI node CRUD calculates cryogen boil-off and stores it into database. Liquid Helium is critical for superConducting magnets and is often referred to as liquid gold.
  • Node CRUD — MRI cryogen consumption calculator
    Node CRUD Cryogen Monitor/Calculator
Python Logo
WordPress
BASH Shell logo

    Bash

  • Bash Scripts
    Bash scripts run across most legacy and modern systems making them extremely portable & useful.
  • Bash scripts — Collection of utilities.
    BASH
DevOps

    devOps

  • devOps deployment
    Docker compose, cron job backups, reverse proxies, Terraform and K8s
  • devOps — continuous development
    TerraForm
    Kubernetes
    BASH
RaspBerry PI Logo

    RaspBerry PI

  • RaspBerry Pi, Multi-server, router & embedded designs
    Compiled Qualcomm QMI modem driver to create an embedded 4G LTE router capable of powering a complete office through a Cisco RV082 dual-wan router & Cisco SPA508G VOIP phone(s) for an industrial wireless LTE office deployment.
  • RaspBerry PI — Multi-server & embedded router design(s)
    4G LTE Router
    4G LTE/Cisco Voip enabled office
    4G LTE connected Raspberry PI Multi Server
AWS Logo
GitHub Logo

    GitHub

  • GitHub Projects
    GitHub repo contains a mix of projects including:
    • MRI service utilities
    • Terraform
    • WordPress
    • Bash
    • Python
  • GitHub — Repository
    GitHub
David

    David Holbrook

  • Possessing a Full spectrum of technical, mechanical. IT, management, services and experience
    Component to system level calibrations, trouble shooting, design and repair solutions.
  • Component level troubleshooting & repair
    • Electronic circuit development, design & manufacturing.
    • PCB fabrication
    • Electrical system & power riser design
    • Oscilloscope, Spectrum analyzer, DVM
    • IoT, embedded, RaspberryPi
    • PC/circuit board soldering and repair.
  • RF calibration, shielding & repair
    • RF coil calibration & repair
    • RF Power calibrations testing & optimization
    • RF shield testing
    • RF door and shield maintenance
    • RF amplifier calibration & repair
  • Superconducting magnet commissioning
    • Ramp/Shim
    • Pre-cool
    • Cryogen Transfill
    • Shieldcooler maintenance, troubleshooting & repair
  • IT. web development & server
    Unix & Linux Systems Administration

    Decades of hands-on Unix and Linux experience beginning with classic System V Unix environments (AT&T 3B2 systems and SunOS, the direct predecessor to Solaris) and continuing through continuous production Debian environments for well over a decade. Debian is both the daily driver and the platform for multi-site hosting with ISPConfig, NGINX, Traefik, Docker, and practical security hardening (TLS, reverse-proxy secret isolation, fail2ban, UFW, least-privilege access, and scheduled off-site backups).

    • Linux server deployment, hardening, security & administration.
    • Web Development — Python, JavaScript
    • Scripting — Python, Bash
    • MariaDB, MySQL, SQLite & PostFix database administration
    • Cloud — AWS deployments
    • Gainesville Dev. Academy — 1st Place App. competition
  • Redundant high availability backups & recovery
    • See Cybersecurity — recovery.
David Pro Cat 1&2 Bike Race

    Pro Cat 1&2 Cycling

  • Pro/Elite Cycling
    Decorated National class cyclist.
  • Accomplishments
    5 X WI State Champion
    2 X Top 5 National Championships
    3 X Junior World Trials Qualifier
© David Holbrook • IT • CyberSecurity • Web Dev • DevOps • Dicom/Pacs • RF & Medical Imaging