Senior Linux System Administrator Jobs in Illinois

Delaware Nation Industries is seeking a Linux System Administrator - Senior to provide advanced systems administration and engineering support for the Air Force Joint Worldwide Intelligence Communications System/Joint Interoperability Test and Services mission. This position will help maintain secure, resilient, and highly available Linux infrastructure across classified and unclassified environments supporting mission-critical operations.

The Senior Linux System Administrator will serve as a technical authority for Linux platforms, virtualization, automation, system security, performance, and lifecycle management. The position requires the ability to independently solve complex problems, lead technical efforts, develop repeatable processes, and coordinate with Government stakeholders and other engineering disciplines.

• Administer, engineer, optimize, and maintain enterprise Linux systems and services across multiple security levels and operational environments.
• Install, configure, harden, patch, upgrade, and decommission Linux operating systems, applications, services, and supporting infrastructure.
• Support Red Hat Enterprise Linux and other approved Linux distributions, including system services, package management, storage, networking, authentication, logging, and performance tuning.
• Design and implement repeatable procedures for system builds, provisioning, configuration management, patching, backup, recovery, restoration, and lifecycle operations.
• Analyze complex system, application, hardware, virtualization, storage, and network problems; conduct root-cause analysis and implement durable corrective actions.
• Monitor system availability, resource utilization, capacity, performance, and security posture; identify risks and recommend improvements before they affect mission operations.
• Administer and troubleshoot VMware or comparable virtualized infrastructure, including virtual machines, images, templates, virtual networking, and storage dependencies.
• Develop and maintain scripts and automation using Bash, Python, Ansible, Puppet, or comparable tools to improve consistency, reduce manual effort, and support troubleshooting.
• Support DevSecOps practices, source-code or configuration repositories, automated workflows, and controlled deployment processes when applicable to the environment.
• Apply DISA STIGs, security baselines, vulnerability-remediation procedures, and other DoD cybersecurity requirements to Linux systems and applications.
• Execute or support ACAS/Nessus scans, vulnerability analysis, remediation, validation, and compliance reporting.
• Maintain secure system access, including accounts, roles, privileges, SSH, authentication services, certificates, keys, and least-privilege controls.
• Support SAN/NAS storage, NFS, iSCSI, file systems, backup infrastructure, and data-transfer services as assigned.
• Support authorized electronic and manual data transfers between network environments and troubleshoot transfer failures, integrity issues, and related operational problems.
• Participate in system integration, testing, acceptance, change control, technical interchange meetings, exercises, and mission-readiness activities.
• Produce and maintain system documentation, architecture diagrams, standard operating procedures, configuration records, plans of action and milestones, and technical reports.
• Provide technical leadership, mentoring, knowledge transfer, and cross-training to Mid-level administrators and other team members.
• Coordinate with cybersecurity, network, Windows, application, database, service desk, and Government teams to resolve escalated incidents and maintain continuity of operations.
• Participate in scheduled maintenance, planned outages, incident response, and after-hours or on-call support as required by the contract.

• Active DoD TS/SCI security clearance.

• At least six (6) years of professional Unix/Linux systems administration experience.
• DoD 8570/8140-compliant IAT III certification, such as CISSP, CASP+ or another current DoD-approved equivalent.
• Demonstrated experience administering enterprise Linux systems in a DoD, intelligence, classified, or similarly regulated environment.
• Strong knowledge of Linux system architecture, networking, storage, system services, access control, logging, troubleshooting, and performance tuning.
• Experience with system backup and recovery, software and patch management, security hardening, vulnerability remediation, and configuration control.
• Experience with virtualization technologies, preferably VMware vSphere and related management components.
• Proficiency with shell scripting and demonstrated ability to automate or streamline system administration tasks.
• Experience diagnosing complex technical issues, performing root-cause analysis, and communicating solutions to technical and nontechnical stakeholders.
• Strong written and verbal communication skills and the ability to work independently, lead technical efforts, and collaborate across functional teams.

• Experience supporting Air Force, JWAC, JITS, Joint, intelligence, or other DoD mission environments.
• Experience with Red Hat Enterprise Linux 7/8/9 or successor supported releases, CentOS, Scientific Linux, Debian, or comparable distributions.
• Experience with Puppet Enterprise, Ansible, CloudBolt, Git, Docker, or comparable automation and DevSecOps technologies.
• Experience supporting multi-level security, cross-domain solutions, classified networks, data-transfer systems, or mission-essential communications environments.
• Experience with ACAS/Nessus, HBSS/endpoint security tools, STIG Viewer, vulnerability-management platforms, or comparable DoD cybersecurity tools.Experience with SAN/NAS technologies, NFS, iSCSI, RAID, LVM, XFS, ext4, ZFS, or other enterprise file systems.
• Experience with DNS, DHCP, NTP, LDAP/Active Directory integration, RADIUS, PKI, certificates, SSH, TCP/IP, and firewall-related troubleshooting.
• Experience with monitoring, logging, configuration-management, ticketing, and IT service-management platforms.
• Bachelor's degree in information technology, computer science, cybersecurity, engineering, or a related field; equivalent experience may be considered.
• Linux, VMware, automation, security, or other relevant industry certifications.