DefSec Systems Administrator – On-Site Helsinki

Reaktor; Helsinki; On-site; EUR 55,000 - 90,000; Full time

Job summary

Reaktor’s Defence & Security Unit is seeking a System Administrator to join our internal IT team in Helsinki. You will build, maintain, and automate our internal IT environments to support high-performing development work, ensuring security, stability, and compliance.

Ideal candidates have 5+ years in system administration, strong Linux, networking and scripting skills, and fluency in Finnish and English. This is a 100% on-site role requiring Finnish citizenship and readiness for security

Qualifications

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

Responsibilities

• Systems Installation & Maintenance – Build and maintain internal IT systems.
• Automation & Infrastructure Development – Improve automation for system maintenance.
• Security & Stability – Ensure environments are safe, compliant, and reliable.
• Cross-functional Collaboration – Partner with DefSec consultants, developers, and stakeholders.
• Support & Troubleshooting – Resolve issues from hardware to networks and automation.
• Documentation & Knowledge Sharing – Document practices and share learnings.
• Continuous Improvement – Evolve internal systems and long-term infrastructure planning.

Skills

Linux

Networking

Scripting

Security

Documentation

Automation

On-site

Communication

Finnish

English

Tools

Ansible

Windows

macOS

Job description

Reaktor’s Defence & Security Unit is seeking a System Administrator to join our internal IT team in Helsinki. You will build, maintain, and automate our internal IT environments to support high-performing development work, ensuring security, stability, and compliance.

Ideal candidates have 5+ years in system administration, strong Linux, networking and scripting skills, and fluency in Finnish and English. This is a 100% on-site role requiring Finnish citizenship and readiness for security