Network Security Engineer Jobs in Reston, VA (NOW HIRING)

VAE, Inc. designs, deploys, and sustains mission-critical enterprise IT environments supporting federal customers. We're seeking an experienced Senior Network Engineer who enjoys hands-on technical work, takes ownership of complex environments, and can operate independently while collaborating with a small, high-performing engineering team.

This role is ideal for a seasoned engineer who prefers deep technical responsibility over people management and values long-term stability in a secure environment. What You'll Do Design, implement, and sustain enterprise network infrastructures supporting high availability and mission operations Serve as a senior technical resource for network troubleshooting, outage resolution, and performance optimization Perform root-cause analysis on complex network issues and drive permanent fixes Configure, maintain, and troubleshoot Cisco and Juniper routing and switching platforms Configure, administer, and troubleshoot Cisco Identity Services Engine (ISE), including policy sets and authentication/authorization workflows Configure and support next-generation firewalls, including Juniper SRX and Cisco Firepower platforms Support firewall rule management, policy validation, and traffic-flow troubleshooting across secured boundaries Maintain accurate technical documentation, diagrams, and standard operating procedures Participate in planning and implementation of network upgrades and architectural improvements Ensure compliance with DoD security and configuration standards Why This Role Own and influence a mission-critical enterprise network, not just tickets Work in a stable, security-focused environment with long-term programs Be part of a small, senior engineering team where expertise is valued Opportunity to deepen skills in network security, access control, and boundary protection8+ years of hands-on network engineering experience in enterprise or government environments Strong understanding of TCP/IP, IPv4, routing, switching, and network troubleshooting Proven experience with Cisco and/or Juniper network devices Hands-on experience configuring and administering Cisco ISE Experience supporting Juniper SRX firewalls and Cisco Firepower (FMC-managed) Strong understanding of firewall policies, security zones, and traffic inspection Familiarity with DoD STIGs and operating in compliance-driven environments CCNA, CCNP, JNCIS, or JNCIP certification (active or previously held) Ability to work on-site in Washington, DC (5 days per week) Active Top Secret clearance (required to start) DoD 8570 IAT Level II certification (Security+ or equivalent) Desired (Nice-to-Have) Skills Experience integrating Cisco ISE with 802.1X, TACACS+, or network access control workflows Exposure to advanced firewall features such as IDS/IPS, URL filtering, or application-layer inspection Familiarity with vulnerability scanning tools (e.g., Nessus) Basic scripting or automation exposure (PowerShell, Ansible, etc.)8+ years of hands-on network engineering experience in enterprise or government environments Strong understanding of TCP/IP, IPv4, routing, switching, and network troubleshooting Proven experience with Cisco and/or Juniper network devices Hands-on experience configuring and administering Cisco ISE Experience supporting Juniper SRX firewalls and Cisco Firepower (FMC-managed) Strong understanding of firewall policies, security zones, and traffic inspection Familiarity with DoD STIGs and operating in compliance-driven environments CCNA, CCNP, JNCIS, or JNCIP certification (active or previously held) Ability to work on-site in Washington, DC (5 days per week) Active Top Secret clearance (required to start) DoD 8570 IAT Level II certification (Security+ or equivalent) Desired (Nice-to-Have) Skills Experience integrating Cisco ISE with 802.1X, TACACS+, or network access control workflows Exposure to advanced firewall features such as IDS/IPS, URL filtering, or application-layer inspection Familiarity with vulnerability scanning tools (e.g., Nessus) Basic scripting or automation exposure (PowerShell, Ansible, etc.)