Secure Systems Administrator - Windows & Linux, SECRET

Aptima Inc.; Dayton (OH); On-site; USD 90,000 - 120,000; Full time

Job summary

Aptima Inc. is seeking a Systems Administrator to support maintenance and sustainment of classified and internal server environments in a security-conscious setting.

The role emphasizes system administration, cybersecurity hardening, and compliance activities to ensure operations meet DoD and NIST requirements. The candidate will collaborate with the ISSM and Aptima Cybersecurity and Compliance Team Lead to implement secure configurations, manage access controls, and document system processes.

Qualifications

• Experience administering Windows and/or Linux server environments in professional, academic, internship, or lab settings.
• Security certification meeting DoD 8570 IAT Level II requirements (minimum CompTIA Security+).
• Experience supporting IT/IS security compliance in secure or regulated environments.
• Familiarity with vulnerability scanning tools such as Tenable or Nessus.
• Understanding of IT/IS governance, risk management, and compliance frameworks including NIST 800-53/800-171.
• Strong organizational, communication, and interpersonal skills.
• Willingness to travel as needed.
• Active SECRET clearance; TS/SCI preferred.

Responsibilities

• Administer and manage Windows and Linux server environments across platforms.
• Maintain security baselines, configurations, and hardening standards.
• Apply DISA STIGs and CIS Benchmarks to systems.
• Perform vulnerability scanning and remediation using tools like Tenable/Nessus.
• Conduct regular audits to ensure IT/IS security compliance.
• Collaborate with IT/IS and cybersecurity teams on secure configurations.
• Manage user access control, identity management, and security protocols.
• Prepare documentation on system configuration, mapping, and processes.
• Assist with accreditation supporting RMF, NIST 800-53, and 800-171.
• Coordinate with auditors during reviews; stay current with standards.

Skills

Windows Admin

Linux Admin

System Hardening

Vulnerability Management

Documentation

Communication

Attention to Detail

Travel Willingness

Team Collaboration

Education

DoD 8570 IAT Level II

CompTIA Security+

Tools

Tenable

Nessus

Job description

Aptima Inc. is seeking a Systems Administrator to support maintenance and sustainment of classified and internal server environments in a security-conscious setting.

The role emphasizes system administration, cybersecurity hardening, and compliance activities to ensure operations meet DoD and NIST requirements. The candidate will collaborate with the ISSM and Aptima Cybersecurity and Compliance Team Lead to implement secure configurations, manage access controls, and document system processes.