Northern Light is seeking an experienced Senior Linux Infrastructure Engineer to take hands-on ownership of our Linux-based infrastructure. In this role, you'll be responsible for operating, maintaining, and evolving a mission-critical environment that runs on a mix of bare-metal and virtualized systems in our private colocation datacenter. This is a highly technical, hands-on position for someone who enjoys working close to the hardware, values operational excellence, and thrives in environments where reliability, security, and scalability matter. What You'll Do • Operate and maintain a Linux infrastructure of ~70 HPE DL360 Gen9/Gen10 bare-metal servers and ~150 virtual machines • Administer RHEL-based systems (primarily Oracle Linux 9), including installation, patching, upgrades, and security hardening • Support virtualization platforms, including: • VMware (5 nodes, ~100 VMs), with potential future migration to Red Hat OVE • KVM-based virtualization supporting Kubernetes workloads (~50 VMs) • Perform on-site datacenter operations in a private six-rack cage, including racking, cabling, labeling, hardware replacement, and decommissioning • Maintain and administer core infrastructure services such as: • Mail relay (Sendmail) • DNS (BIND) • SFTP (ProFTPd) • LDAP-backed authentication and authorization • Package repository mirroring (Foreman) • Centralized automation and orchestration (Ansible Automation Platform) • On-prem GitLab Premium for version control and CI/CD • Develop and maintain standard operating procedures covering: • Inventory management (NetBox) • Monitoring, alerting, and observability (LogicMonitor) • Incident response and root-cause analysis • Vulnerability and patch management (Tenable One) • Backup, recovery, and disaster recovery (Veeam) • Participate in incident response, scheduled maintenance, and post-incident reviews • Collaborate with vendors, service providers, and internal engineering, security, and operations teams • Support secure, compliant infrastructure that enables product delivery and business needs What We're Looking For: • We're looking for someone with 7+ years of Linux systems engineering experience, including at least 3 years as the primary owner of infrastructure at scale - not a contributor on a team, but the person accountable for uptime, security, and reliability. RHEL-based distributions are required; Oracle Linux 9 is strongly preferred • BS or MS in Computer Science, Computer Engineering, Information Technology, or equivalent practical experience • Demonstrated ability to manage the full server lifecycle end-to-end: OS installation and hardening, configuration management, patching cadence, capacity planning, and decommissioning • Deep proficiency with Linux system internals: kernel tuning, systemd service management, storage subsystems (LVM, RAID, NFS/NAS), and network stack configuration (bonding, VLANs, firewall rules via firewalld/iptables) • Proven experience designing and maintaining high-availability and redundant architectures in production - not just operating them • Direct, hands-on experience with HPE ProLiant (or equivalent enterprise) servers, including iLO/IPMI management, firmware updates, hardware diagnostics, and component replacement • Experience performing all physical datacenter tasks independently: rack and stack, structured cabling, labeling, power management, and hardware lifecycle tracking in a private colo or equivalent environment • Production-level administration of VMware vSphere/ESXi environments (vCenter, VM lifecycle, resource pools, snapshots, HA/DRS) and KVM-based virtualization (libvirt, virt-manager, bridged/NAT networking); experience supporting platform migrations (e.g., VMware to open-source hypervisors) is a strong plus • Hands-on experience building and maintaining Ansible playbooks and roles for configuration management, OS hardening, and orchestrated change deployment - not just running existing playbooks • Demonstrated experience administering production DNS (BIND), LDAP-backed authentication, mail relay, and SFTP services - including troubleshooting, zone management, schema modifications, and integration with downstream systems • Experience managing on-prem package repository infrastructure (Foreman or equivalent) and enforcing controlled patching workflows across a large server fleet • Hands-on experience with enterprise monitoring and alerting platforms (LogicMonitor, Zabbix, Nagios, or equivalent), including building meaningful alerting thresholds and dashboards; active experience with vulnerability management tools (Tenable, Qualys, or equivalent): scan interpretation, remediation prioritization, and patch compliance tracking • Experience owning backup and disaster recovery operations end-to-end: policy design, Veeam (or equivalent) administration, recovery testing, and DR runbook maintenance • Track record of leading incident response, conducting post-mortems, and producing root-cause analyses with lasting corrective actions; strong technical documentation discipline (SOPs, runbooks, infrastructure diagrams) and ability to communicate clearly to both technical and non-technical stakeholders • Familiarity with Docker and Kubernetes • Solid networking fundamentals with hands-on experience collaborating with network teams on switches, firewalls, and load balancers; sufficient depth to independently scope and escalate network-adjacent infrastructure issues • On-site presence required at a private colocation facility in Somerville, MA; datacenter work may involve elevated noise levels and variable temperatures; limited after-hours or weekend maintenance (historically ~3-5 times per year) Job Type: Full-Time Work authorization requirements: Must be authorized to work in the United States (unfortunately, we cannot sponsor visas). Location: Must be local to Boston/Somerville area, with shared on-site presence required between the office and a Somerville-based colocation data center