System Administrator (Defence & Security)

Reaktor’s Defence & Security Unit is looking for a System Administrator to join our internal IT team in Helsinki.

Join Reaktor’s DefSec team, where agility, teamwork, and trust drive everything we do. We work on some of the most complex and mission-critical challenges in the industry, helping clients navigate an evolving landscape with cutting-edge solutions.

Are you in your element when maintaining and building secure, automated IT environments that support world-class development work? Do you enjoy solving complex technical challenges hands-on while working alongside dedicated professionals? If so, you might be just the person we’re looking for.

What you’ll be doing

• Systems Installation & Maintenance – Build and maintain DefSec’s internal IT systems that enable high-performing development work.
• Automation & Infrastructure Development – Maintain and improve automation for system maintenance, using state-of-the-art tooling.
• Security & Stability – Ensuring our environments are safe, compliant, and reliable.
• Cross-functional Collaboration – Partner with DefSec consultants, developers, and stakeholders to solve complex and multi-dimensional challenges.
• Support & Troubleshooting – resolving issues from hardware to networks and automation.
• Documentation & Knowledge Sharing – Document practices and systems, and actively share your learnings with the team.
• Continuous Improvement – Help evolve our internal systems and support organization, taking ownership of both day-to-day operations and longer-term infrastructure planning.

To thrive in this position, you’ll need

• Minimum of 5 years of relevant experience in system administration or IT infrastructure roles.
• Strong knowledge of Linux (Fedora, CentOS, or similar).
• Understanding of IP networking, VPNs, and firewalls.
• Familiarity with certificate management and authentication mechanisms.
• Hands-on experience with scripting (Bash, Python, PowerShell, etc.).
• A proactive mindset with a focus on helping others and solving problems.
• Excellent communication skills to interact with both technical and non-technical stakeholders.
• Fluency in both Finnish and English (written & spoken)
• Willingness to work 100% on-site .

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.
• Coding 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

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 .