IT Security Engineer III

About this role

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.

If you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo — because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 — and moving faster than anyone else dares.

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.

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