IT Security Engineer III

Leidos Holding$107K — $195K *
Aerospace & Defense
5 - 7 years of experience
Job Overview by Ladders

Qualifications

  • Bachelor's degree in IT, Cybersecurity, Computer Science, or equivalent experience.
  • 7+ years of experience in network security or infrastructure engineering.
  • Strong understanding of enterprise networking principles such as TCP/IP, Routing, BGP, OSPF, and VLANs.
  • Experience with enterprise firewall platforms, specifically Fortinet and Cisco ASA/Firepower.
  • Proven ability to troubleshoot complex security issues across multi-vendor environments.

Responsibilities

  • Design and maintain network security solutions for NASA mission environments.
  • Lead engineering efforts for security platforms including Fortinet and Cisco ASA/Firepower.
  • Serve as the technical lead for complex infrastructure and security projects.
  • Develop secure network architectures and guidelines for enterprise environments.
  • Evaluate and recommend emerging security technologies for adoption.
  • Collaborate with various teams to deliver integrated security solutions.
  • Mentor junior engineers and provide technical leadership.

Benefits

  • Opportunity to work on mission-critical projects with NASA.
  • Collaborative work culture with diverse teams.
  • Support for professional development and industry certifications.
  • Involvement in cutting-edge security technologies and practices.
  • Flexible working arrangements including after-hours support.
Full Job 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:
Pay Range $107,900.00 - $195,050.00

The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.

About Leidos Holding

Leidos Holding Careers

Joining Leidos Holding presents an unparalleled opportunity to advance one's career with a leader in innovation and technology. The company offers a plethora of job opportunities aimed at fostering professional growth and development in a diverse and inclusive environment.

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Leidos Holding is actively seeking skilled professionals who are passionate about leveraging their expertise to drive innovation and leadership in their fields. With a variety of open positions, Leidos Holding provides a platform for individuals to challenge themselves in a dynamic work environment.

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At Leidos Holding, innovation is at the core of everything they do. Employees are encouraged to think creatively and push boundaries. The company supports this drive for innovation through comprehensive professional development and diversity training programs that are designed to enhance skills and foster leadership.

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Leidos Holding is committed to creating a workplace where diversity is not only recognized but celebrated. With a culture that values and promotes diversity, Leidos Holding ensures that all team members have the opportunity to contribute, learn, and grow.

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For those starting their career, Leidos Holding offers internship programs that provide a robust foundation in the industry. Internships are a great way to develop essential skills, gain valuable work experience, and build professional networks.

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Employees at Leidos Holding enjoy a range of benefits designed to support their professional and personal lives. The company culture is built on a foundation of respect and integrity, providing a supportive and collaborative environment where every team member is valued.

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Leidos Holding encourages its employees to engage in networking within the company to discover new opportunities for career advancement. The leadership team at Leidos Holding is dedicated to supporting employees in their career paths with ample opportunities for networking and growth.

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