Didi L.

I am a System Administrator specializing in Linux infrastructure, email systems, web server administration, and secure, high-availability IT operations. I support end-to-end production environments by ensuring uptime, optimizing performance, and implementing strong security controls across all systems. My primary expertise lies in Debian/Ubuntu environments, covering installation, configuration, hardening, and lifecycle maintenance. I have deep experience with Postfix, Exim, and Dovecot, including advanced tuning, deliverability restoration, and full deployment of SPF, DKIM, and DMARC. I troubleshoot DNS and rDNS issues, remediate blacklist/spam problems, and stabilize mail platforms affected by misconfiguration or degraded reputation. I also administer and optimize Apache and Nginx web servers, including virtual host setups, SSL/TLS, reverse proxy configurations, caching, and performance tuning. I manage hosting environments for PHP-based applications (WordPress, Laravel, custom sites) and Python applications (Flask, Django, FastAPI), ensuring proper runtime configuration, dependency management, process supervision (systemd, gunicorn/uwsgi), and application-level security. Beyond email and application hosting, I oversee networking, firewall management, virtualization, cloud platforms, monitoring instrumentation, log analytics, and backup frameworks. My workflow emphasizes documentation, operational resilience, and adherence to best-practice security standards. Whether you need immediate troubleshooting, infrastructure hardening, application environment optimization, or long-term maintenance, I deliver clean, reliable, and well-documented solutions designed for stability and minimal downtime. Core Competencies: • Linux Server Administration (Debian / Ubuntu) • Email Systems: Postfix, Exim, Dovecot • DNS, rDNS & Email Deliverability (SPF, DKIM, DMARC) • Web Servers: Apache / Nginx (performance tuning, SSL/TLS, reverse proxy) • PHP & Python Application Environments (WordPress, Laravel, Flask, Django) • Server Hardening, Security Baselines & Firewall Management • Monitoring, Log Analysis & Incident Response • Backup Strategy, Disaster Recovery & Data Integrity • Virtualization & Cloud: KVM, AWS, Linode Let’s work together to secure, stabilize, and optimize your infrastructure.