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.

What we’re looking for

At least 8 years of relevant experience in system administration or IT infrastructure.

Proven experience in gathering requirements, prioritising a team backlog, and balancing conflicting demands.

Demonstrated ability to work directly with business stakeholders and align technical priorities with business needs.

Good communication skills with both technical and non-technical stakeholders.

Strong knowledge of Linux, such as Fedora, CentOS, or similar.

Good understanding of IP networking, VPNs, and firewalls.

Familiarity with certificate management and authentication mechanisms.

Hands-on scripting experience with Bash, Python, PowerShell, or similar.

Fluency in both Finnish and English (written & spoken).

Willingness to work primarily on-site in Helsinki.

This position requires Finnish citizenship due to client and security regulations. The selected candidate must successfully complete a security clearance process.

Nice-to-have skills

Experience with Ansible or similar automation tools.

Familiarity with Windows and macOS desktop administration.

Programming experience in TypeScript, Python, or Go.

Why join us?

For two decades, we’ve been developing qualities and capabilities for adapting, reacting, and supporting change – building Reaktor to hold up in a fast-paced environment while ensuring the well-being of our people.

While working at Reaktor, we’ll provide you with

An opportunity to work with our DefSec’s internal IT team to ensure our consultants have access to secure and efficient environments. Your work directly supports our critical security-focused software projects.

The ability to impact how you work. Together with your team, you choose the approach, technologies, and methodologies you think will work best in any given situation.

A community with as much support as your heart desires.

A team that’s not only experienced but considerate as well – they all want you to succeed.

Career development, helping you develop your skills further through guidance and/or courses, and giving you the opportunity to explore your career interests.

A sustainable work-life balance and support for your daily life outside of work. (e.g., free moving day, Reaktor car share, sick child care services, office space to use for your private events, etc.).

Many different hobby clubs, from winter swimming and running to knitting and archery, that bring people together outside of (and sometimes inside) office hours. Many of these are supported by Reaktor.

Interested? Drop us a line – We'll be happy to hear from you!

Diversity, equity, and inclusion

Together, we are committed to making Reaktor an environment that embraces and values all of our employees for the whole of who they are. We encourage applicants from all backgrounds to apply, knowing that studies show that members of underrepresented communities don’t apply for jobs unless they fully satisfy all of the requirements. If you're thinking twice about applying for this reason, we invite you to send us your application anyway. You could be just the person we're looking for.

Read more about our DEI work here .