Senior System Administrator – Hybrid (Brussels)

About the role

We are seeking a Senior System Administrator to maintain and modernise a highly secure IT infrastructure. Working in a multidisciplinary team, you will ensure the reliability of server environments, virtualization platforms and critical services while driving continuous improvement.

Key responsibilities

• Administer Windows and Linux servers, including Active Directory, GPO, DNS and DHCP.
• Manage and optimise virtualisation platforms such as VMware, Proxmox and Hyper‑V.
• Implement security measures, patch management, backups and business‑continuity procedures.
• Design scalable system architectures and support infrastructure modernisation projects.
• Automate routine tasks using PowerShell, Bash or Python.
• Troubleshoot complex infrastructure issues and collaborate with network and security teams.
• Maintain up‑to‑date technical documentation and participate in migration initiatives.

Required profile

• Minimum 7 years of experience in Windows and Linux system administration.
• Strong expertise in virtualisation, storage and infrastructure security.
• Proven experience with large‑scale Active Directory environments.
• Analytical, solution‑oriented mindset with the ability to work under pressure.
• Native or fluent Dutch or French, with active technical English.
• TOP SECRET security clearance.

Required skills

• Windows Server
• Linux
• Active Directory, Group Policy, DNS, DHCP
• VMware, Proxmox, Hyper‑V
• PowerShell, Bash, Python scripting
• Azure or AWS (plus)
• Infrastructure security, patch management, backup solutions

What we offer

• Hybrid work model with up to two remote days per week.
• Fixed‑term contract until June 2026, renewable.
• Opportunity to work in a technically advanced, secure environment.