Đorđe Kaurinović

Systems Administrator / Systems Architect

Profile

20+ years designing and running production IT infrastructure where downtime and data loss are not an option. Focused on architecture that is secure, documented and maintainable - from networking and virtualization to backup and post-incident recovery. I come to the table with solutions, not a list of problems.

Technical Expertise

Windows
Windows Server, Active Directory, GPO, DNS/DHCP, PowerShell
Unix/Linux
FreeBSD (OPNsense), Debian/Ubuntu, LVM, systemd, rsyslog, bash
Virtualization
Hyper-V, Proxmox VE
Cloud & DevOps
Cloudflare (DNS, WAF, Workers, Email Routing, SSL/TLS), GitHub (repositories, CI/CD, releases), Docker
Networking
segmentation (VLANs, subnets, inter-VLAN firewall policies), IPSec site-to-site VPN, FortiGate, OPNsense, Omada SDN, Tailscale
Security
vulnerability management (Greenbone/OpenVAS), centralized logging with integrity protection (hash chain), DNS logging, server and web service hardening, DMARC/SPF/DKIM
Databases
MS SQL Server (backup strategies, SQL Agent, object security and ownership, migrations)
Storage & Backup
SAN/NAS/DAS, Synology, BTRFS, URBackup, image and file-level backup of Hyper-V environments, disaster recovery
Monitoring
ntopng, NetAlertX, SmokePing, AdGuard Home, Unbound (DoT, DNSSEC)
GIS
GeoServer, AutoCAD, spatial data (EPSG:3908, GeoPackage), georeferencing
Development & Automation
PowerShell, Python, C#/.NET, Node.js, React, PHP/Laravel
AI-assisted Engineering
Claude / Claude Code in production work: agentic workflows, MCP integrations, context engineering. Delivery of infrastructure and web solutions with human review of architecture, security and data models.

Key Experience

  • Design and operation of AD domains and Hyper-V infrastructure (SQL, GIS, web and application servers)
  • Site-to-site IPSec VPN links between separate networks and organizations
  • Segmented networks with multiple VLANs and inter-zone firewall policies
  • Backup and disaster recovery: production restored after a ransomware attack, no ransom paid
  • Centralized logging for forensic readiness (DHCP, firewall, DNS, log integrity protection)
  • Technical specifications for procurement of server, network and GIS equipment

Projects

  • Vihor IP Scanner - author; open-source network scanner for Windows (MIT), Microsoft Store / GitHub
  • cyber-security.ba - founder and author of an IT security portal