Senior Linux Systems Engineer — Remote, Secure Infra

Lumen; Madison (WI); Remote; USD 83,000 - 111,000; Full time

Job summary

Lumen is seeking a Senior Linux Systems Administrator to design, build, secure, operate, and maintain Linux-based infrastructure supporting a classified federal program. The role emphasizes advanced Linux admin, VMware/KVM virtualization, automation, and on-going lifecycle management for a remote US-based team.

The candidate will deploy, patch, and harden Ubuntu and RHEL, manage LDAP/AD integrations, certificate lifecycles, and Nessus vulnerability workflows, while contributing to DevOps

Qualifications

• 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.

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, 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

Skills

Linux systems

Ubuntu

RHEL

Bash scripting

VMware ESXi

vCenter / vSphere

KVM virtualization

Nessus

SSL/TLS certs

LDAP/AD integration

TCP/IP networking

Ansible

Python

Git

Zabbix

Elastic Stack

REST APIs

Flask/Django

GitLab CI/CD

Kubernetes

Tools

Ubuntu

RHEL

Job description

Lumen is seeking a Senior Linux Systems Administrator to design, build, secure, operate, and maintain Linux-based infrastructure supporting a classified federal program. The role emphasizes advanced Linux admin, VMware/KVM virtualization, automation, and on-going lifecycle management for a remote US-based team.

The candidate will deploy, patch, and harden Ubuntu and RHEL, manage LDAP/AD integrations, certificate lifecycles, and Nessus vulnerability workflows, while contributing to DevOps