Application/System Administrator (m/f/d)

We are looking for a Senior Application/System Administrator (m/f/d) who takes responsibility for the secure operation and continuous development of our infrastructure. This is a hands‑on role that requires a proactive, solution‑oriented mindset and strong technical expertise.

Due to project requirements, applicants must hold German or EU citizenship.

This position requires on-site presence.

Your Responsibilities

• Operation and administration of servers, storage systems, databases, and virtual machines
• Support and maintenance of a Public Key Infrastructure (PKI) across Linux and Windows environments
• Ensuring stability, performance, and security of the IT infrastructure
• Identifying and implementing process optimizations, especially through automation
• Supporting security‑related measures and ensuring the stability and performance of the PKI environment
• Troubleshooting and resolving issues across Windows and Linux systems
• Handling incidents and service requests in line with ITSM standards
• Participation in a 24/7 on‑call rotation to ensure system availability

Your Profile

• Several years of proven experience in administering Linux (RedHat/RHEL) and Windows server environments
• Good knowledge of VMware ESXi and VMware vCenter administration
• Excellent skills in application administration and operations
• Strong understanding of complex application landscapes
• deep understanding of how applications interact and depend on each other
• ability to quickly grasp technical relationships and end‑to‑end flows
• experience with multi‑tier architectures (frontend, backend, middleware, databases)
• confident debugging of complex error scenarios, especially in integration‑heavy environments
• Good knowledge of databases, preferably PostgreSQL and Oracle
• Experience in managing Public Key Infrastructure (PKI)
• Proficiency with web servers and middleware such as Apache HTTP Server, Apache Tomcat, and JBoss
• Experience with monitoring tools, ideally CheckMK
• Knowledge in IT process automation (e.g., scripting, configuration management tools)
• Solid understanding of networking and security concepts (routing, firewalls, segmentation)
• Analytical, structured, and independent working style
• Strong team spirit and willingness to participate in a 24/7 on‑call rotation
• Motivation for continuous learning and professional development
• Network & Security: Routing, software firewalls, NetApp
• Web & Middleware: Apache HTTP Server, Apache Tomcat, JBoss