David Álvarez
Systems Administrator | DevSecOps | Cybersecurity Specialist
About Me
Systems administrator specializing in cybersecurity, incident response, and perimeter infrastructure. Extensive experience managing Linux/Windows Server environments, virtualization via Proxmox/LXC/Docker, and web service hardening. Practical focus on automation, resilient infrastructure engineering, and proactive threat monitoring.
Technical Skills
| Category | Technologies // Tools |
|---|---|
| Operating Systems | Linux (Debian, Ubuntu, SLES), Windows Server |
| Infrastructure & Virtualization | Proxmox VE, LXC, Docker, VirtualBox, Infrastructure as Code |
| Networking & Perimeter Security | Firewalls, ACLs, NAT, VPNs, TCP/IP, DNS, DHCP, LB, SSL/TLS, Filtering Rules |
| Web Services & Applications | Nginx, Apache, PHP, WordPress, NextCloud, Reverse Proxies |
| Scripting & Automation | Bash, Python, GoLang |
| Database Administration | MySQL, MariaDB, SQL Server, SQLite |
Professional Experience
Perimeter Security Specialist (SOC)
Telefónica Cybersecurity & Cloud Tech S.L. | July 2026 – Present
- Administration, operation, and optimization of perimeter security infrastructures and policies.
- Implementation and maintenance of filtering rules, NAT policies, VPN tunnels, and Access Control Lists (ACLs).
- Security event and incident monitoring, analysis, and response.
- Troubleshooting and resolving complex connectivity, access control, and network security issues.
Tier 2 Systems Administrator
Stellantis - Altia S.A. | February 2026 – June 2026
- Continuous administration and maintenance of production servers across Linux and Windows infrastructures.
- Tier 2 incident resolution within critical infrastructure and application ecosystems.
- Proactive performance monitoring, in-depth log analysis, and preventive bottleneck resolution.
- End-to-end database management for applications (installation, maintenance, backup, and restore policies).
Web Developer & SEO Analyst & DBA (ERASMUS+)
Quantum21 Ltd. (Larnaca, Cyprus) | March 2025 – June 2025
- Design, development, and architecture of WordPress-based websites.
- Custom theme and plugin development using PHP.
- Web performance optimization (Core Web Vitals, caching strategies, and asset compression).
- Search engine visibility audits and enhancements via technical SEO.
Education
- Bachelor’s Degree in Computer Science – UNIR (2026 – 2028)
- Specialization Course in Cybersecurity in IT Environments – IES de Teis (2025 – 2026)
- Higher National Diploma (HND) in Network Systems Administration (ASIR) – IES de Teis (2023 – 2025)
- High School Diploma in Science & Technology – IES de Mos (2021 – 2023)
Certifications
Official Technical Certifications:
Featured Projects
High Availability Home Lab:
Multi-node personal environment consisting of 2x Lenovo m920x, Raspberry Pi 5, and 4x Custom PCs running Proxmox VE, Debian 13, and LXC containers. Hosts local and public-facing services under strict isolation policies and reverse proxying.
Pentest Stack (Web Audit Framework):
Modular tool written in Bash to automate web security audits (vulnerability scanning, DNS enumeration, and security header analysis). Available on GitHub.