Network Security Engineer, Lead

Join AMERICAN SYSTEMS as a Lead Network Security Engineer supporting a critical national security mission in a highly classified environment onsite in Dallas, TX
. This role combines hands-on network and firewall engineering with technical leadership, helping strengthen secure, resilient enterprise connectivity. Salary range:
USD $155,000 - $180,000 per year
.

• Lead secure network engineering, administration, and operational support within a highly classified environment.
• Design, implement, configure, and maintain enterprise network infrastructure, including routers, switches, VLANs, ACLs, VPNs, network segmentation, and high-availability architectures.
• Administer, monitor, and troubleshoot enterprise firewall environments.
• Configure and manage firewall policies and access rules, including NAT, VPNs, security zones, logging, and monitoring.
• Support and troubleshoot Cisco Firepower and Firepower Management Center (FMC);
  Cisco Firepower experience is preferred.
• Troubleshoot complex Layer 2 and Layer 3 issues across routing, switching, firewalling, connectivity, and access control.
• Support AAA and network access control requirements (authentication, authorization, accounting).
• Configure and troubleshoot 802.1X
  , VPN, and network access control solutions.
• Support Cisco ISE environments, including authentication, authorization, policy enforcement, and network access control;
  Cisco ISE experience is preferred.
• Support RMF and STIG activities, including secure configuration, vulnerability remediation, and compliance.
• Develop and maintain network diagrams, implementation plans, SOPs, configuration documentation, and technical reports.
• Partner with cybersecurity, systems administration, and mission teams to deliver secure, resilient network solutions.
• Support incident response, outage resolution, root cause analysis, change implementation, and network remediation.
• Monitor network performance and recommend improvements to enhance security, availability, reliability, and performance.
• Provide technical leadership and guidance to network engineering and operations personnel.

• U.S. citizenship required.
• Active TS/SCI clearance with SAP eligibility required.
• Bachelor’s degree in a related technical field, or additional relevant experience in lieu of a degree.
• 8+ years of experience in network engineering, network operations, or network security.
• Experience in enterprise, defense, intelligence, federal government, or highly regulated environments.
• Strong hands-on enterprise networking skills: routing and switching, Layer 2 and Layer 3 troubleshooting, VLANs and subnetting, ACLs, network addressing and design, VPN technologies, network segmentation, and resilient network architectures.
• Hands-on experience administering and troubleshooting enterprise firewalls.
• Experience with one or more firewall platforms:
  Cisco Firepower/FMC (preferred), Palo Alto Networks, Fortinet, Check Point, or other commercial or government enterprise firewalls.
• Experience with firewall policy administration, NAT, VPNs, security zones, logging, monitoring, and troubleshooting.
• Experience supporting AAA, 802.1X, RMF, STIG, secure configuration, and network access control requirements.
• Cisco ISE experience preferred, especially authentication, authorization, accounting, policy enforcement, and network access control.
• Active DoD 8140/8570 IAT II certification such as Security+ CE, CySA+, SSCP, or equivalent.
• Experience troubleshooting Cisco routers, switches, firewalls, and enterprise network infrastructure.
• Ability to work independently, lead technical efforts, and resolve complex network and security issues.
• Strong written and verbal communication skills.

Cisco Firepower, Firepower Management Center…