CSfC Network Engineer Subject Matter Expert (SME)

Leidos is seeking an experienced Network Engineer (SME) to join our Integrated Information Technology Support Services (I3TS) team, who will support an extensive digital modernization program critical to Defense Threat Reduction Agency (DTRA) in Fort Belvoir, VA. The Network Engineer will work closely with the Leidos and Government technical leadership team to help drive innovation, growth, and efficiencies within the I3TS portfolio.Clearance: Must have an active TS/SCI clearance at time of consideration. U.S. Citizen is a must.Primary Responsibilities: The Commercial Solutions for Classified (CSfC) Network & Security Engineer will architect and operate secure, dual-layer cryptographic boundaries utilizing Cisco and Aruba IPsec/SSL VPNs and dynamic routing (BGP/OSPF) in strict compliance with NSA Capability Packages. In this role, you will author and tune Palo Alto NGFW security policies and IDS/IPS threat prevention signatures, implement enterprise network access control and 802.1X policies via Cisco ISE and Aruba ClearPass, integrate enterprise PKI/OCSP services and hardened NTP, and generate key engineering artifacts required for NSA CSfC PMO registration and compliance auditing.Architect, deploy, and maintain CSfC infrastructure operating within Black/Gray/Red networks.Design, configure, and maintain multi-layered Commercial Solutions for Classified (CSfC) architectures in alignment with NSA Mobile Access (MA), Multi-Sight (MSC) Capability Packages, with Campus Wireless LAN (WLAN) experience a bonus. Ensure strict compliance with vendor diversity and dual-tunnel encryption mandates.Understanding of NIAP approved list and monitors for changesDesign, configure, and maintain multi-layered Commercial Solutions for Classified (CSfC) architectures in alignment with NSA Capability Packages (MSC, MA, and CWLAN). Ensure strict compliance with vendor diversity and dual-tunnel encryption mandates.Implement enterprise routing protocols (BGP, OSPF) alongside redundant outer and inner IPsec VPN tunnels across Cisco and Aruba appliances. Configure remote access SSL VPNs and ensure end-to-end traffic separation.Author, optimize, and audit Palo Alto Next-Generation Firewall (NGFW) security policies, App-ID, User-ID, and URL filtering. Configure and tune Palo Alto IDS/IPS threat signatures, anti-spyware, and vulnerability protection.Architect and manage Cisco Identity Services Engine (ISE) and Aruba ClearPass policy managers for 802.1X network access control, RADIUS/TACACS+ administration, posture assessment, and endpoint profiling.Integrate enterprise Public Key Infrastructure (PKI) components, managing X.509 certificate lifecycles, Certificate Authorities (CAs), CRL/OCSP validation, and hardened, authenticated Network Time Protocol (NTP) infrastructure.Prepare CSfC compliance artifacts, Key Management Plans (KMPs), Continuous Monitoring Plans (CMPs), and registration packages for NSA CSfC PMO submission.Basic Qualifications:Bachelor's degree or higher in Computer Science, Information Technology, Engineering, Engineering Management, Management Information Systems, or related STEM degree program, and 12-15 years of relevant experience. Specific experience, education and training may be considered in lieu of degree.12+ years of progressive network engineering experience within DoD/DoW, federal, or defense contractor enterprise environmentsActive TS/SCI ClearanceActive DoD 8570.01-M / DoD 8140 IAT Level II or III baseline certification (e.g., Security+ CE, CySA+, CASP+, or CISSP).Active Computing Environment certification, including one or more of: Cisco CCNA, CCNP, Aruba ACSA or ACSPProven expertise configuring Cisco (IOS-XE/ASR) and Aruba (Mobility Controllers/Gateways) IPsec and SSL VPNs, including IKEv2, Suite B/CNSA cryptography, and dynamic routing (BGP, OSPF).Demonstrated engineering experience with Palo Alto Networks firewalls (PAN-OS), Panorama central management, and advanced IDS/IPS inspection profiles.Hands-on deployment experience with both Cisco ISE and/or Aruba ClearPass implementing 802.1X, EAP-TLS authentication, and role-based access policies.Strong working knowledge of X.509 certificates, CA hierarchy integration, certificate revocation lists (CRLs), OCSP, and secure NTP stratum synchronization.Direct prior experience preparing and successfully registering NSA CSfC Capability Package solutions (Mobile Access, Multi-Site Connectivity, or Campus WLAN).Deep understanding of Commercial National Security Algorithm (CNSA) Suite requirements, post-quantum readiness considerations, and hardware security modules (HSMs).Familiarity with Ansible, for automating network device configuration backups, policy compliance checks, and certificate rotations.Certified in any of the following - Cisco CCNP/CCIE (Security or Enterprise), Palo Alto PCNSE, Aruba Certified ClearPass Expert (ACCX), or Aruba Certified Mobility Expert (ACMX).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:September 3, 2026For 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 -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.SummaryLocation: Fort Belvoir, VAType: Full time