Principal Network Security Engineer

Leidos is seeking an experienced Principal Network Security Engineer to design, engineer, and implement enterprise network security capabilities across a large, distributed network environment. The role is responsible for advancing network security architecture through the execution of strategic design and implementation efforts that improve the security posture, segmentation, access control, and resiliency of the enterprise network.

This position is responsible for overall network security engineering support across a broad range of efforts, including planning, designing, and evaluating the security components of the network. Duties include providing specifications for network security architecture, evaluating and recommending new technologies to enhance current capabilities, performing needs assessments, and directing the installation, configuration, testing, and tuning of network security infrastructure.

The successful candidate serves as a technical leader and subject matter expert — assessing the current security architecture, defining the controls and segmentation model the enterprise needs, building practical implementation plans with realistic risk and rollback provisions, and directing a team of engineers to deliver them under aggressive timelines.

Scope and Impact

Impact: Influences development of solutions that impact strategic project and program goals and business results. Recommends and develops new technical solutions, products, and security standards. Leads and manages the work of other technical staff that has significant impact on project results and outputs.

Complexity: Resolves highly complex problems through significant application of technical knowledge, conceptualization, reasoning, and interpretation. Develops solutions that are highly innovative and achieved through research and integration of best practices.

Communication: Communicates with government, program, cybersecurity, and technical leadership on matters of significant technical importance. Presents security architecture recommendations, implementation plans, risks, dependencies, and status to technical leadership, cybersecurity authorities, stakeholders, and approval boards, and works to build consensus around new concepts, practices, and approaches.

Knowledge: In-depth understanding of network security principles, theories, and concepts and their application across a range of programs. Serves as a subject matter expert within the network security domain.

Primary Responsibilities:

Network Security Engineering and Architecture

Design, engineer, and implement enterprise network security architecture spanning next-generation firewalls, intrusion detection and prevention, web and TLS proxies, VPN and encryption services, network access control, DNS security, and east-west security controls.

Evaluate the current network security architecture, identify gaps and improvement opportunities, estimate level of effort, assess implementation risk, and develop practical engineering plans to strengthen enterprise security capabilities.

Lead network segmentation and secure connectivity efforts, including data-flow mapping, security-zone and enclave design, firewall rule set and ACL review and rationalization, routing and security policy coordination, cutover sequencing, validation, and stakeholder approval.

Design and implement network access control and device-posture enforcement (Comply-to-Connect style), including identity and device authentication, posture assessment, policy enforcement points, remediation workflows, and phased enforcement rollout.

Advance zero-trust-aligned networking, micro-segmentation, least-privilege access policy, and encrypted-transport strategies across the enterprise.

Provide specifications for network security architecture, evaluate and recommend emerging security technologies, and perform needs assessments to inform design and investment decisions.

Engineer secure connectivity between on-premises, cloud, and remote environments, including IPsec and TLS VPN, secure cloud interconnects, and perimeter and boundary protection designs.

Tune and optimize security controls to reduce false positives, close coverage gaps, and improve detection and enforcement without degrading network performance or availability.

Project Execution

Drive security engineering projects from concept through implementation, including architecture evaluation, requirements analysis, dependency identification, design coordination, planning, execution, validation, and transition to operations.

Develop and manage implementation plans, schedules, cutover strategies, contingency plans, rollback procedures, validation steps, stakeholder communications, and change documentation for mission-critical security changes.

Coordinate change windows, maintenance activities, test validation, and rollback procedures for high-impact security policy and infrastructure changes.

Partner with network architecture, cybersecurity, operations, project management, and technical SME teams to resolve blockers, manage dependencies, and reduce delivery risk.

Support accreditation and compliance activities, including security control implementation, STIG application, vulnerability remediation, POA&M support, and the technical artifacts required for authorization.

Technical Leadership

Serve as the senior technical authority for network security design decisions, providing technical direction, mentoring, and day-to-day guidance to network and security engineers, administrators, and analysts.

Organize technical priorities, track details across concurrent efforts, manage competing demands, and maintain accountability against aggressive schedules.

Provide clear, well-reasoned technical information and recommendations to government stakeholders and approval authorities.

Continuously improve engineering processes, documentation standards, implementation playbooks, migration runbooks, technical standards, and execution models to accelerate delivery, reduce rework, improve operational handoff, and lower sustainment burden.

Documentation

Develop and maintain engineering and operational documentation, including:

Network security architecture and logical/physical design diagrams

Data-flow diagrams, security-zone models, and segmentation designs

Firewall policy standards, rule set baselines, and ACL documentation

Port, protocol, and services (PPS) requirements

Implementation and cutover plans with rollback and contingency procedures

Test and validation plans

Risk, dependency, and decision registers

Security control implementation statements and accreditation artifacts

Technical standards, playbooks, runbooks, and standard operating procedures

As-built and operations transition documentation

Required Qualifications:

Bachelor's degree or equivalent experience and 12+ years of prior relevant experience, or Master's degree with 10+ years of experience. Specific experience, education, and training may be considered in lieu of a degree.

Significant experience designing and implementing network security architecture in complex, large-scale enterprise environments.

Experience serving as a senior technical lead directing the work of network and security engineers, administrators, analysts, or implementation resources.

Experience leading security engineering projects from planning through implementation, including requirements analysis, dependency management, risk reduction, contingency planning, execution oversight, validation, and operational transition.

Hands-on engineering experience with next-generation firewalls, intrusion detection and prevention systems, proxies and TLS inspection, VPN and encryption services, and network access control platforms.

Experience with network segmentation or similar secure connectivity efforts, including data-flow analysis, firewall and ACL policy review, routing changes, securit