Senior Linux Administrator (Active Clearance)

The Senior Linux Systems Administrator will design, build, secure, operate, and maintain Linux-based infrastructure supporting a classified federal program. The position is primarily focused on advanced Linux administration, VMware and KVM virtualization, infrastructure deployment, authentication services, vulnerability management, certificate administration, monitoring, and network connectivity., * Design and build secure Linux infrastructure from initial requirements through production implementation and operational handoff.

• Install, configure, administer, patch, harden, and troubleshoot Ubuntu and Red Hat Enterprise Linux systems.
• Perform advanced command-line administration using Bash and standard Linux diagnostic and management utilities.
• Administer VMware ESXi, vCenter, and vSphere environments, including hosts, virtual machines, templates, storage, virtual networking, certificates, resource allocation, backups, and recovery.
• Build and maintain KVM-based virtualization environments and support evaluation or migration between virtualization platforms.
• Provision physical and virtual servers and integrate them with network, storage, DNS, NTP, directory, monitoring, backup, and security services.
• Install, configure, maintain, and troubleshoot LDAP and Active Directory integrations, including LDAP, LDAPS, bind accounts, directory searches, groups, permissions, and certificate trust.
• Manage the SSL/TLS certificate lifecycle, including private keys, certificate requests, SANs, certificate installation, chain validation, renewal, expiration tracking, and trust troubleshooting.
• Administer Nessus vulnerability-scanning infrastructure, maintain scan configurations and schedules, analyze findings, and support remediation and validation.
• Maintain monitoring and logging platforms such as Zabbix and Elastic Stack.
• Troubleshoot network connectivity involving routing, DNS, ports, protocols, firewalls, switches, NAT, access controls, and application-to-system communication.
• Create and maintain automation using Ansible, Bash, and Python.
• Use Git and GitLab CI/CD to manage infrastructure code, scripts, configurations, and deployment workflows.
• Read, troubleshoot, and make limited modifications to applications or services developed with frameworks such as Flask or Django.
• Support REST API integration between applications, infrastructure platforms, and network or security elements.
• Develop and maintain accurate build guides, system diagrams, configuration records, operational procedures, backup procedures, and recovery documentation.
• Participate in system upgrades, incident response, problem management, capacity planning, and lifecycle management.
• This position requires between 5-20% Travel to accommodate customer meetings and servicing hardware on-site

The successful candidate must be comfortable building infrastructure from the ground up and supporting it throughout its operational lifecycle. The role also includes DevOps and application-support responsibilities, including infrastructure automation, configuration management, source control, CI/CD, API integration, and troubleshooting applications that interface with network and security systems., * Six or more years of experience in Linux systems, infrastructure, network, security, or platform administration.

• Advanced administration experience with Ubuntu and RHEL.
• Strong command-line proficiency, including Bash scripting and CLI-based troubleshooting.
• Demonstrated experience designing and building production infrastructure from the ground up.
• Hands-on experience administering VMware ESXi, vCenter, and vSphere.
• Experience with KVM or comparable Linux-based virtualization technology.
• Experience administering Nessus or a comparable vulnerability-management platform.
• Experience managing SSL/TLS certificates and public-key infrastructure concepts.
• Strong knowledge of LDAP, LDAPS, and Active Directory integration.
• Working knowledge of TCP/IP, routing, DNS, NTP, firewalls, switching, ports, and network troubleshooting.
• Experience with Ansible and infrastructure automation.
• Working knowledge of Python and Git.
• Experience supporting monitoring and logging tools such as Zabbix and Elastic Stack.
• Ability to troubleshoot across operating systems, virtualization, authentication, applications, and network infrastructure.
• Active TS clearance with current SSBI/T5R investigation and CI polygraph, if those remain mandatory for the program.

Preferred qualifications

• Experience with GitLab CI/CD.
• Experience supporting Flask or Django applications.
• Familiarity with Kubernetes and containerized services.
• Experience with REST APIs and network-device integrations.
• Experience with backup, disaster recovery, and high-availability design.
• Experience supporting firewalls, switches, and network-security platforms.
• Familiarity with security hardening and compliance requirements for classified or government systems.

This information reflects the anticipated base salary range for this position based on current national data. Minimums and maximums may vary based on location. Individual pay is based on skills, experience and other relevant factors.

Location Based Pay Ranges:

$82,969 - $110,625 in these states: AL, AR, AZ, FL, GA, IA, ID, IN, KS, KY, LA, ME, MO, MS, MT, ND, NE, NM, OH, OK, PA, SC, SD, TN, UT, VT, WI, WV, and WY.

$87,117 - $116,156 in these states: CO, HI, MI, MN, NC, NH, NV, OR, and RI.

$91,266 - $121,688 in these states: AK, CA, CT, DC, DE, IL, MA, MD, NJ, NY, TX, VA, and WA.

Lumen offers a comprehensive package featuring a broad range of Health, Life, Voluntary Lifestyle benefits and other perks that enhance your physical, mental, emotional and financial wellbeing. We’re able to answer any additional questions you may have about our bonus structure (short-term incentives, long-term incentives and/or sales compensation) as you move through the selection process.

Lumen is the trusted network for the AI-powered world, connecting people, data, and applications through our expansive fiber network and connected ecosystem. We enable secure, high-performance connectivity across cloud, edge, and AI workloads for enterprises, governments, and communities.

At Lumen, you’ll work on infrastructure customers rely on today and build for what’s next, where performance, security, and resilience matter.

This is a high accountability environment where bold ideas drive real innovation for our customers, partners, and industry. The work is challenging, expectations are clear, and trust is built into how we operate. If you’re ready to take ownership, deliver meaningful impact, and help shape the future of AI-ready connectivity, join us today., Life at Lumen is human and connected, even in a fast moving, AI-focused organization. We set clear expectations and trust people to meet them. With real support and shared accountability, teams collaborate better, move faster, and deliver meaningful outcomes.

Our Lumen 8 behaviors guide how we interact, make decisions, and work together, shaping a culture built to perform and win.

To learn more about Life at Lumen and how we live the Lumen 8, please visit