Security-Focused Systems Administrator (Windows/Linux)

Aptima; Dayton (OH); On-site; USD 90,000 - 130,000; Full time

Job summary

Aptima in Dayton, OH is seeking a qualified IT security professional to join our classified and internal server environments team. You will perform system administration, cybersecurity hardening, and compliance activities to keep critical research systems secure.

The role requires collaboration with the ISSM and cybersecurity teams to maintain secure configurations, conduct vulnerability management, and support RMF, NIST 800-53/800-171 documentation.

Qualifications

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

Responsibilities

• Administer and secure Windows and Linux server environments
• Support the maintenance, sustainment, and security configuration of classified and internal server environments
• Apply and maintain system hardening standards such as DISA STIGs and CIS Benchmarks
• Perform vulnerability scanning and remediation using tools such as Tenable, Nessus, or similar platforms
• Conduct regular system audits to ensure compliance with IT/IS security frameworks and governance requirements
• Collaborate with IT/IS and cybersecurity teams to plan and implement secure system configurations
• Manage user access control, identity management, and security protocols
• Prepare and maintain documentation related to system configuration, mapping, processes, and service records
• Assist with accreditation and compliance documentation supporting RMF, NIST 800-53, and NIST 800-171 requirements
• Coordinate with internal and external auditors to support compliance reviews and assessments
• Stay current with evolving cybersecurity standards, tools, and regulatory requirements

Skills

Strong organizational skills

Attention to detail

Strong communication

Interpersonal skills

Willingness to travel

Education

Security+ (DoD 8570 IAT Level II)

Tools

Tenable

Nessus

Job description

Aptima in Dayton, OH is seeking a qualified IT security professional to join our classified and internal server environments team. You will perform system administration, cybersecurity hardening, and compliance activities to keep critical research systems secure.

The role requires collaboration with the ISSM and cybersecurity teams to maintain secure configurations, conduct vulnerability management, and support RMF, NIST 800-53/800-171 documentation.