Senior Linux Administrator (Active Clearance)

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. The Role 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. 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. Location This is a remote opportunity open to candidates located anywhere in the U.S. The Main Responsibilities 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,…