Freelance Senior System Administrator – 1‑Year Contract

About the role

We are looking for a Freelance Senior System Administrator to design, implement and maintain a high‑performance, secure and scalable IT infrastructure for a Belgian client. The role is hybrid (3 days on‑site, 2 days remote) and runs for a one‑year contract.

Key responsibilities

• Manage on‑premises and cloud systems (Linux, Windows, virtualization, containers).
• Implement server configurations, patch management and performance tuning.
• Design, deploy and maintain virtualized environments (VMware, Proxmox, Hyper‑V).
• Automate tasks with Bash, PowerShell and Python scripts.
• Ensure network security, performance and uptime (firewalls, VPNs, load balancers, monitoring).
• Manage storage solutions (NAS, SAN, backup/recovery).
• Develop and test disaster‑recovery and business‑continuity plans.
• Monitor health, performance and security using Nagios, Zabbix or Prometheus.
• Collaborate with security teams to enforce ISO 27001, GDPR and other policies.
• Lead infrastructure upgrades, migrations and scaling projects.
• Mentor junior administrators and provide technical guidance.

Required profile

• 7+ years of system administration or infrastructure engineering experience, with at least 3 years in a senior or lead role.
• Fluent in English and French or Dutch for client communication.
• Strong leadership, problem‑solving and stakeholder‑management abilities.

Required skills

• Linux and Windows Server administration
• Virtualization (VMware, Proxmox, Hyper‑V)
• Containerization
• Cloud platforms (AWS, Azure, GCP)
• Scripting/automation (Bash, PowerShell, Python)
• Monitoring tools (Nagios, Zabbix, Prometheus)
• Logging (ELK Stack)
• Networking (TCP/IP, DNS, DHCP, VPN, firewalls)
• Configuration management (Ansible, Puppet, Chef)
• Security standards (ISO 27001, GDPR, Active Directory)
• Disaster‑recovery and business‑continuity planning