The Senior IT Security Engineer is a key member of the IT Security Engineering team, protecting the backbone of our hybrid infrastructure and enabling secure innovation. This role shapes how systems are designed, defended, and evolved against real-world cyber threats. Working in a collaborative, hands-on environment, it blends architectural ownership with deep technical expertise and a shared security-first mindset.

• Design, operate, and continuously improve security infrastructure across on-premise and cloud environments, including Next-Gen Firewalls (NGFW), Load Balancers, and WAF solutions
• Implement and optimize defenses against DDoS attacks, bot traffic, and API-based threats, leveraging platforms such as F5 Distributed Cloud
• Lead the technical design, testing, and rollout of new security solutions and architectures
• Ensure secure integration of services within Azure, VMware, and existing on-prem environments
• Design and maintain email security solutions, including Secure Email Gateways (SEG) and enforcement of DMARC, SPF, and DKIM policies
• Monitor security events and logs, lead incident investigations, and drive root cause analysis
• Manage PKI and certificate lifecycles to ensure encrypted and trusted communications
• Act as a subject matter expert for IT security, advising teams and stakeholders on best practices during projects and change initiatives
• Participate in a shared on-call rotation to ensure availability of critical security services

• Several years of experience in IT security engineering or network security within complex on-premise, cloud, or hybrid environments
• Strong understanding of networking fundamentals, including TCP/IP, routing, switching, and the OSI model
• Hands-on experience with enterprise security and networking platforms such as Next-Gen Firewalls (e.g. Palo Alto Networks, Fortinet/FortiGate), VMware NSX micro-segmentation, and Azure Firewalls
• Solid expertise in load balancing and application delivery using technologies such as F5 BIG-IP, VMware Avi (NSX ALB), Azure Load Balancers, and Application Gateways, as well as Web Application Firewall (WAF) and IPS solutions
• Practical experience with cyber defense mechanisms including DDoS mitigation, bot protection, and API security, ideally with platforms such as F5 Distributed Cloud
• Deep understanding of email security architectures, including Mail Transfer Agents (MTA), Secure Email Gateways (e.g. Proofpoint, Mimecast, Microsoft Defender for Office 365, Cisco IronPort), and authentication standards (SPF, DKIM, DMARC)
• Experience managing Public Key Infrastructure (PKI) and certificate lifecycles to support encrypted communications
• Comfortable working in Linux/Unix environments, with exposure to automation or scripting tools such as Python, Ansible, PowerShell, or Terraform
• Familiarity with security standards and best practices (e.g. ISO 27001, OWASP Top 10), ITSM processes, and basic Windows Server / Active Directory concepts is a plus
• Analytical, security-first mindset with strong communication skills and professional command of written and spoken English

Greentube believes great work happens when people feel supported, inspired, and balanced. By investing in its employees, the company creates an environment where everyone can thrive and reach their full potential. That's why Greentube offers:

• Flexible working hours and a hybrid work model, supported by a strong culture of work-life balance
• A dedicated training budget to explore new skills, deepen expertise, and actively shape career development
• A welcoming office atmosphere at the Vienna HQ with daily fresh fruit, a wide selection of teas, fair-trade coffee, and meals at a company-subsidized restaurant
• Subsidized public transportation, along with access to pool e-bikes and e-cars for business and personal use
• Numerous opportunities to stay active and connected, including an on-site fitness room, MyClubs app points, and regular sports and company events
• Attractive local employee discounts and healthcare benefits that support everyday well-being
• A competitive base salary range of 80.000 - 85.000 EUR gross per year (paid in 14 salaries), aligned with industry standards and adjusted based on qualifications, skills, and relevant experience