IT Security Engineer III

Leidos; Huntsville (AL); On-site; USD 108,000 - 195,000; Full time

Job summary

Leidos is seeking an experienced IT Security Engineer III to join the AEGIS Security Infrastructure Engineering team supporting NASA’s mission environments. You will architect, implement, and manage enterprise network security across a large multi-vendor environment, collaborating with operations, program leadership, and customer stakeholders to ensure secure, scalable solutions.

You will lead complex deployments, guide architecture decisions, and mentor junior engineers while maintaining

Qualifications

• 7+ years of experience in network security, cybersecurity, or infrastructure engineering.
• Strong understanding of enterprise networking including: TCP/IP, Routing & Switching, BGP, OSPF, VLANs, NAT, High Availability, VPN technologies.
• Experience engineering and administering Fortinet and Cisco ASA/Firepower platforms.
• Experience designing secure network architectures in large enterprises.
• Experience troubleshooting complex security and networking issues across multi‑vendor environments.

Responsibilities

• Design, engineer, implement, and maintain enterprise network security solutions for NASA mission environments.
• Lead engineering efforts involving Fortinet, Cisco ASA/Firepower, SASE, WAF, VPNs and other platforms.
• Serve as the technical lead for complex deployments and security modernization projects.
• Develop secure network architectures and provide guidance for new/existing environments.
• Perform advanced troubleshooting and root-cause analysis of complex security issues.
• Create implementation plans, diagrams, standards and operational procedures.
• Lead change management activities including reviews and post-change validation.
• Evaluate emerging security tech and make adoption recommendations.
• Collaborate with cybersecurity, networking, operations, and cloud teams.
• Ensure security infrastructure complies with NASA/federal requirements and best practices.
• Mentor junior engineers and provide technical leadership across programs.

Skills

Network security

Technical leadership

Written/verbal communication

Documentation

Education

Bachelor’s degree in IT/Cybersecurity/CS or related field

Tools

Fortinet

Cisco ASA/Firepower

SASE

Web Application Firewall (WAF)

VPN technologies

Job description

Description

We are seeking an experienced IT Security Engineer III to join the AEGIS Security Infrastructure Engineering team supporting the NASA AEGIS Program. This role is responsible for the design, engineering, implementation, and lifecycle management of enterprise network security infrastructure supporting NASA's mission-critical environments.

The IT Security Engineer III serves as a senior technical resource responsible for architecting, implementing, and supporting complex security solutions across a large-scale, multi-vendor enterprise environment. This position works closely with operations teams, architects, program leadership, and customer stakeholders to develop secure, scalable, and resilient infrastructure while ensuring compliance with NASA security standards and federal requirements.

Primary Responsibilities

• Design, engineer, implement, and maintain enterprise network security solutions supporting NASA mission environments.
• Lead engineering efforts involving Fortinet, Cisco ASA/Firepower, Secure Access Service Edge (SASE), Web Application Firewalls (WAF), VPN technologies, and other enterprise security platforms.
• Serve as the technical lead for complex infrastructure deployments, modernization initiatives, and security enhancement projects.
• Develop secure network architectures and provide technical guidance for new and existing enterprise environments.
• Perform advanced troubleshooting, root cause analysis, and resolution of complex network security issues.
• Develop implementation plans, engineering documentation, network diagrams, standards, and operational procedures.
• Lead change management activities including technical reviews, implementation planning, and post-change validation.
• Evaluate emerging security technologies and provide recommendations for adoption within the enterprise.
• Collaborate with cybersecurity, network engineering, operations, cloud engineering, and customer stakeholders to deliver integrated security solutions.
• Ensure enterprise security infrastructure complies with NASA, federal, and industry security requirements and best practices.
• Mentor junior engineers and provide technical leadership across engineering initiatives.
• Participate in after-hours maintenance windows and provide escalation support as required.

Basic Qualifications

• Ability to obtain a Public Trust Clearance.
• Bachelor's degree in Information Technology, Cybersecurity, Computer Science, or a related field, or equivalent experience.
• 7+ years of experience in network security, cybersecurity, or infrastructure engineering.
• Strong understanding of enterprise networking including:
  • TCP/IP
  • Routing and Switching
  • BGP
  • OSPF
  • VLANs
  • NAT
  • High Availability
  • VPN technologies
• Experience engineering and administering enterprise firewall platforms such as Fortinet and Cisco ASA/Firepower.
• Experience designing and implementing secure network architectures within large enterprise environments.
• Experience troubleshooting complex security and networking issues across multi-vendor environments.
• Experience following structured change management and engineering lifecycle processes.
• Strong written and verbal communication skills with the ability to present technical concepts to both technical and non-technical audiences.

Preferred Qualifications

• Industry certifications such as:
  • Fortinet Network Security Expert (FCP, FCSS, FCX)
  • Cisco CCNP Security or CCIE Security
  • CISSP
  • GIAC certifications
• Experience with:
  • Fortinet Security Fabric
  • Cisco ASA/Firepower
  • Secure Access Service Edge (SASE)
  • Web Application Firewalls (WAF)
  • IPsec VPN technologies
  • PKI and certificate management
  • Zero Trust architectures
• Experience supporting cloud security platforms
• Experience working in large enterprise, federal government, or Department of Defense environments.
• Experience supporting highly available, mission-critical infrastructure.
• Demonstrated ability to lead engineering projects and mentor junior engineers.

Original Posting

July 28, 2026

For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above.

Pay Range

$107,900.00 - $195,050.00

About Leidos

Leidos is an industry and technology leader serving government and commercial customers with smarter, more efficient digital and mission innovations. Headquartered in Reston, Virginia, with 47,000 global employees, Leidos reported annual revenues of approximately $16.7 billion for the fiscal year ended January 3, 2025. For more information, visit www.Leidos.com.

Pay And Benefits

Pay and benefits are fundamental to any career decision. That's why we craft compensation packages that reflect the importance of the work we do for our customers. Employment benefits include competitive compensation, Health and Wellness programs, Income Protection, Paid Leave and Retirement. More details are available at www.leidos.com/careers/pay-benefits.

Securing Your Data

Beware of fake employment opportunities using Leidos' name. Leidos will never ask you to provide payment-related information during any part of the employment application process (i.e., ask you for money), nor will Leidos ever advance money as part of the hiring process (i.e., send you a check or money order before doing any work). Further, Leidos will only communicate with you through emails that are generated by the Leidos.com automated system – never from free commercial services (e.g., Gmail, Yahoo, Hotmail) or via WhatsApp, Telegram, etc. If you received an email purporting to be from Leidos that asks for payment-related information or any other personal information (e.g., about you or your previous employer), and you are concerned about its legitimacy, please make us aware immediately by emailing us at [e-mail].

If you believe you are the victim of a scam, contact your local law enforcement and report the incident to the U.S. Federal Trade Commission.

Commitment to Non-Discrimination

All qualified applicants will receive consideration for employment without regard to sex, race, ethnicity, age, national origin, citizenship, religion, physical or mental disability, medical condition, genetic information, pregnancy, family structure, marital status, ancestry, domestic partner status, sexual orientation, gender identity or expression, veteran or military status, or any other basis prohibited by law. Leidos will also consider for employment qualified applicants with criminal histories consistent with relevant laws.