Senior IT Systems Administrator

About Castelion

Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. We're designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts.

Senior IT Systems Administrator

We are seeking a highly skilled and security-focused Senior IT Systems Administrator to join our team. In this role, you will be expected to be a leader in the design, implementation, maintenance, and security of critical IT infrastructure in compliance with DoD and industry standards. We want to give you the autonomy you need to shine and show what you've got! Ideally, you'll thrive as someone who is able to handle senior level systems projects end-to-end with minimal oversight, while still delivering high quality work!

Responsibilities

• Administer, maintain, and secure Linux and Windows based server environments.
• Manage cloud IaaS and virtualization platforms including Microsoft Azure, AWS, and on-premises platforms.
• Implement and maintain system hardening in compliance with DoD STIGs, NIST frameworks, CMMC, and more.
• Monitor system performance, conduct root cause analysis, and resolve complex infrastructure issues.
• Ensure system availability and disaster recovery through backups, patch management, and redundancy planning.
• Manage user and group lifecycles in Microsoft 365.
• Collaborate with cybersecurity teams during audits, incident response, and vulnerability remediation.
• Lead IT infrastructure projects including upgrades, migrations, and system deployments.
• Document system configurations, procedures, and changes to maintain accurate and secure records.
• Train and mentor junior IT staff, promoting a culture of compliance and technical excellence.

Required Qualifications

• 7 years of experience in systems administration in a secure, enterprise IT environment.
• Strong experience with Linux and Windows Servers
• Strong in automation and scripting - ideally tools like PowerShell, Python, Bash, Azure Automation, Logic Apps, etc.
• In-depth knowledge of virtualization and enterprise storage systems.
• Familiarity with cybersecurity compliance frameworks.
• Strong knowledge with endpoint protection, SIEM tools, and monitoring for performance and security.
• Strong problem-solving, documentation, and communication skills.

Preferred Qualifications

• Industry certifications such as CompTIA Security or CISSP.
• Experience building and managing Kubernetes.
• Experience managing Linux desktops or laptops as end-user devices.
• Experience with automation tools (Ansible, Terraform, Puppet, PowerShell DSC).
• Understanding of Zero Trust architecture and secure enclave designs.
• Active Security Clearance

Work Environment & Conditions

• On-site work; some after-hours/on-call support may be necessary.
• Occasional lifting of IT equipment (up to 40 lbs) and data center work.

Leadership Qualities

• Bias to Action and Creative Problem Solving. Desire and experience questioning assumptions in ways that lead to break through ideas that are ultimately implemented. Successfully bring in applicable processes/concepts/materials from other industries to achieve efficiency gains. Ability to personally resolve minor issues in development without requiring significant support.
• High Commitment, High Initiative. A successful candidate will have a genuine passion for Castelion's mission and consistently look for ways to contribute to the company's technical goals and prevent hardware blockers. Ability to work in a fast paced, autonomously driven, and demanding atmosphere. Strong sense of accountability and integrity.
• Clear Communicator. Proactively communicates blockers. Trusted in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. Capable of tactfully managing relationships with stakeholders to achieve company-desired outcomes without compromising relationships. Emails, IMs and verbal interactions are logical, drive clarity, and detailed enough to eliminate ambiguity.

ITAR Requirements

• To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State.

Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.

All employees are granted long-term stock incentives as part of their employment at Castelion. All employees receive access to comprehensive medical, vision, and dental insurance, and the company offers four weeks of paid time off per year.