Lead System Administrator (Defence & Security)

Reaktor's Defence & Security Unit is looking for an experienced, hands-on Lead System Administrator to join our internal IT team in Helsinki.

Our team builds and maintains secure and reliable IT environments that DefSec's development teams depend on. The work ranges from daily maintenance and troubleshooting to automation, security, and longer-term infrastructure development.

As a Lead System Administrator, you will work hands-on as part of the team: building and maintaining systems, developing automation, and solving technical problems. Alongside your technical responsibilities, you will take ownership of the overall flow of the team's work.

You will keep the backlog clear, bring together technical and business needs, and facilitate prioritisation together with the team and business stakeholders. In our low-hierarchy environment, your role is to help the team maintain a shared understanding of what matters most, navigate competing requirements, and move the right work forward.

What you'll be doing

Owning, maintaining, and refining the team's backlog to ensure clear direction and steady workflow.

Setting priorities for upcoming work based on business impact, urgency, and technical dependencies.

Building and maintaining DefSec's internal IT systems.

Developing automation for system maintenance and infrastructure management.

Ensuring that our environments are secure, compliant, stable, and reliable.

Troubleshooting issues across hardware, operating systems, networks, and automation.

Working closely with developers, business stakeholders, and consultants to understand and translate their needs into actionable work.

Improving documentation, sharing knowledge, and developing the team's technical practices.

Contributing to both day-to-day operations and longer-term infrastructure planning.