About the role: PMAT is seeking a highly experienced System Administrator III to provide senior-level administration, sustainment, troubleshooting, security hardening, and technical leadership across Windows, Linux, virtualization, network, and tactical computing environments. This role supports the stability, security, performance, and availability of servers, systems, network infrastructure, and mission-focused IT environments while helping guide remediation, patching, compliance, backup and recovery, monitoring, and infrastructure improvement efforts. The candidate will work closely with IT, cybersecurity, engineering, data, cloud, and operational teams to support secure enterprise and tactical systems in government or defense-related environments. The role requires senior-level technical judgment, hands-on administration expertise, strong communication skills, and the ability to support both technical execution and team coordination. Responsibilities: • Lead and support administration of Windows, Linux, ESXi, network, and tactical computing environments by managing installation, configuration, updates, monitoring, troubleshooting, optimization, and sustainment activities. • Implement and maintain security hardening across systems and network infrastructure by supporting CMMC alignment, DISA STIG implementation, vulnerability remediation, patching, access control, threat monitoring, and secure configuration management. • Assess, research, and remediate vulnerabilities by investigating exploits, evaluating cyber risk, coordinating recommended fixes, applying security updates, and documenting remediation actions. • Develop, implement, and maintain backup and recovery procedures to protect data, preserve system availability, validate recovery processes, and support continuity of operations. • Manage and troubleshoot network infrastructure, including routers, firewalls, VPNs, network devices, connectivity issues, routing, DNS, DHCP, and related enterprise or tactical network services. • Support tactical systems and data architecture by troubleshooting tactical environments, deploying and monitoring tactical data pipelines, improving data flow reliability, and supporting edge server, embedded GPU, and containerized workloads. • Monitor infrastructure products, hardware, software, licenses, system performance, compatibility, and End-of-Life considerations to support sustainment planning and infrastructure modernization. • Provide senior-level coordination and technical guidance to administrators, end users, cybersecurity teams, engineers, and program stakeholders by documenting technical solutions, mentoring team members, communicating status, and supporting issue resolution. Required Skills and Experience: • Extensive experience in system administration, network administration, IT infrastructure, tactical systems support, or related technical infrastructure roles. • Strong experience administering Windows and Linux operating systems, including Red Hat, CentOS, Rocky Linux, or similar enterprise Linux environments. • Experience managing servers, virtualization environments, network infrastructure, VPNs, hardware, software, system updates, backup and recovery, monitoring, and troubleshooting activities. • Strong understanding of cybersecurity, access control, vulnerability remediation, patch management, system hardening, network hardening, and secure configuration practices. • Experience supporting enterprise, tactical, government, military, or mission-focused IT environments requiring high standards for security, reliability, and compliance. • Strong understanding of networking concepts and protocols such as TCP/IP, DNS, DHCP, VPNs, routing, firewalls, ports, and network troubleshooting. • Strong analytical, problem-solving, time management, multitasking, and prioritization skills in a fast-moving technical environment. • Strong written and verbal communication skills with the ability to explain technical issues, risks, remediation actions, and recommendations to IT, cybersecurity, engineering, program, and operational stakeholders. Preferred Skills and Experience: • Senior-level experience leading or supervising teams of network administrators, system administrators, IT specialists, or technical infrastructure personnel. • Experience with CMMC compliance, DISA STIG guidelines, operating system hardening, network hardening, security assessment tools, vulnerability scanning tools, and cyber remediation workflows. • Experience with shell scripting, automation, and configuration tools such as Bash, Python, Ansible, PowerShell, or similar technologies. • Experience with virtualization and containerization technologies such as VMware, Docker, Kubernetes, or related platforms. • Experience with cloud and enterprise services such as Amazon Web Services, GCC High, Microsoft 365, Azure, Intune, or related environments. • Experience with edge servers, embedded GPUs, tactical computing hardware, Jetson Nano, DGX Spark, or similar mission hardware. • Experience deploying, monitoring, troubleshooting, and improving tactical data pipelines or tactical data architecture in operational or test environments. • Previous experience working with government agencies, Navy organizations, military users, or Department of War mission environments. • Experience maintaining detailed system documentation, configuration records, troubleshooting procedures, license tracking, End-of-Life planning, and infrastructure sustainment artifacts. Education and Certification Requirements: • Bachelor's Degree or Equivalent Experience • Current Security+ Certificate Citizenship and Clearance Requirements: • U.S. Citizenship required • No dual citizenship • SECRET security clearance required • TS/SCI Eligible security clearance a plus Location/Address: • 100% On-site • San Diego, CA, NAVWAR Travel & Passport: 5%, CONUS and OCONUS Work Environment: PMAT offices as needed. In some cases, work in a government facility may be required. Travel may be required for customer engagement, team coordination, and potentially for business development.