Senior System Administrator – Linux

About the role

We are looking for a highly experienced Senior System Administrator to lead the design, deployment, and maintenance of secure data‑management platforms in defence‑aligned environments. Reporting directly to the President, you will own critical infrastructure across multiple on‑premises sites and ensure compliant, high‑performing IT operations.

Key responsibilities

• Architect, deploy and maintain a resilient Linux server environment.
• Manage Active Directory, Group Policy, IAM and network configurations.
• Configure and support firewalls, routers, switches, VLANs, DNS and IAM integrations.
• Lead system lifecycle activities: installation, configuration, testing and troubleshooting.
• Provide end‑user support and resolve technical access issues.
• Oversee patch management, compliance, change control and vulnerability remediation.
• Implement system hardening aligned with the Essential Eight and conduct regular security audits.
• Maintain and optimise production Kubernetes clusters, including deployment, scaling, monitoring (Prometheus/Grafana) and troubleshooting.
• Collaborate with internal teams and external stakeholders, delivering technical insights to leadership.
• Provide technical leadership and mentorship to engineering teams.

Required profile

• Minimum 10 years of experience in system administration or IT infrastructure.
• Proven leadership, accountability and curiosity in complex, secure environments.
• Strong analytical and troubleshooting capability.
• Experience leading or mentoring technical teams.

Required skills

• Linux system administration.
• Active Directory and Group Policy.
• Identity & Access Management (IAM).
• Networking (CCNA/CCNP level or equivalent hands‑on experience).
• Scripting with PowerShell, Bash and Python.
• Kubernetes production environments.
• Monitoring tools: Prometheus, Grafana.
• System hardening and security frameworks (Essential Eight).
• Patch management, vulnerability remediation.