IONOS SE

Linux - System Administrator (f/m/d) Defense Products

at subsidary IONOS SE in Karlsruhe
Full-time | Permanent | Professionals
Reference ID: I-1567

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About us

IONOS is the leading European digitalization partner for small and medium-sized businesses (SMB). The company serves around six million customers and operates across 18 markets in Europe and North America, with its services being accessible worldwide. With its Web Presence & Productivity portfolio, IONOS acts as a 'one-stop shop' for all digitalization needs: from domains and web hosting to classic website builders and do-it-yourself solutions, from e-commerce to online marketing tools. In addition, the company offers Cloud Solutions to enterprises who are looking to move to the cloud as their businesses evolve.   

Join our highly motivated team of experts dedicated to combating cybersecurity threats. As a System Administrator, you will plan and operate our cutting-edge defense platforms alongside site reliability engineers and network engineers. These platforms are crucial for protecting our hosting products and infrastructure, encompassing classic DDoS mitigation, modern Web Application Firewalls (WAF), Zero Trust strategies, and our Content Delivery Network (CDN). We foster a culture that highly values creative ideas, agile working methods, initiative, and participation.

As an Specialist in our Defense squad, you act as a vital shield against daily DDoS and sophisticated cyber attacks. You are the first line of defense, dedicated to neutralizing threats through technical mastery and proactive mitigation.
We are hiring for this role in Karlsruhe and/or Berlin. You will join a distributed, international Defense Platform Services team of approximately 8–9 experts. You will work within specialized squads for Operations, SRE, and NRE to provide comprehensive protection for the group’s infrastructure across Germany and beyond.

Tasks

The day-to-day operations of the Defense Platform Services team directly correlate to the financial stability of the United Internet Group. When our defenders succeed, the group’s digital economy remains fluid; your success is measured by the silence of a neutralized threat.
  • Active Defense & DDoS Mitigation: Administer and troubleshoot scrubbing platforms and a complex, large-scale proxy infrastructure. You will engage in the "cat and mouse game" of fighting attacks in real-time—identifying, washing, and neutralizing malicious traffic to protect core cloud and fiber services.
  • Architectural Density & Operational Excellence: You will manage the lifecycle of 800+ Linux-based components within a highly available infrastructure. To maintain 24/7 group-wide protection, this role requires a mandatory on-call service rotation of one week per month, ensuring immediate response to high-priority network threats.
  • Innovation & Data-Driven Defense: We leverage modern AI tools for log analysis and pattern detection. You will bring creative ideas to the table, utilizing the ELK Stack and ClickHouse to manage high-volume telemetry, identify attack signatures, and devise advanced mitigation strategies.
  • Lifecycle & Pipeline Management: Develop and optimize CI/CD pipelines in an agile DevOps environment. You will evaluate and integrate new technologies—including Docker and Kubernetes—to ensure our defense architecture remains lean, efficient, and ahead of evolving industry threats.

Qualifications

Because this role manages critical national and corporate infrastructure, the barrier to entry involves both technical mastery and a high degree of professional trust.Therefore, we require 3 to 5 years of platform operating experience at scale. We are looking for an administrator with a "security gene"—a specialized, proactive interest in DDoS mitigation and cyber defense that goes beyond standard system maintenance.
  • Expert-level proficiency in managing complex, distributed Linux environments.
  • Proven experience configuring Nginx as a reverse proxy or Web Application Firewall (WAF).
  • Practical knowledge of BGP, Flowspec, and Anycast routing.
  • A passion for eliminating repetitive tasks through Ansible, Puppet, and Python.
  • Several years of experience in the administration of complex, distributed Linux systems.
  • Proven experience in configuring and operating Nginx as a reverse proxy or web application firewall.
  • Hands-on experience with the deployment of BGP, Flowspec, and Anycast routing on Linux systems and network routers.
  • Strong passion for automation using tools like Ansible, Puppet, and Python to eliminate repetitive manual tasks.
  • Strong analytical skills to evaluate DDoS attacks, implement effective countermeasures, and continuously develop our defense platforms.
  • Initial experience with technologies such as Docker, Kubernetes, ClickHouse, or the ELK Stack is beneficial.
  • Like us, you are a strong advocate for Open Source, especially Linux.

Benefits

  • Hybrid working model.
  • Flexible working hours through trust-based working hours.
  • Subsidized canteen and various free drinks at select locations.
  • Modern office space with excellent public transport connections.
  • Various employee discounts for activities and products.
  • Employee events such as summer and winter parties, as well as workshops.
  • Numerous training and development opportunities.
  • Various health offerings, such as sports and wellness courses.

apply online now

Diversity enriches. Different cultures, nationalities, genders, ages, sexual orientations and religions as well as people with disabilities - we value diversity and encourage it. Because only teams that reflect all facets of society offer the best environment for creativity and make a company productive and distinctive. We value diversity and welcome all applications.

Contact

Fragen?

IONOS SE
Recruiting Team IONOS

Hinterm Hauptbahnhof 3-5
D-76137 Karlsruhe
jobs@ionos.com

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