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Linux System Administrator

Lisbon, Lisbon, PortugalPosted 3 months ago
Full-timehybridMid-Senior Level

Job Description

Ensure the availability, performance, and security of Linux Server environments and related services for multiple clients by delivering operations, automation, and Level 2/3 support with on call duty.

CONTEXT

  • Shared services team of 5 administrators supporting multiple client environments (multi-tenant).
  • Responsible for operational availability, performance, and security of Linux infrastructure across on-prem and cloud.
  • Rotating on-call to ensure service continuity per contractual SLAs.

Main Responsibilities:

System administration:

  • Install, configure, and maintain Linux servers (e.g. Ubuntu, Debian, CentOS, RHEL).
  • Perform regular patching, upgrades, and system hardening.
  • Manage users, groups, permissions, and sudo/access policies.
  • Ensure system stability, performance, and capacity planning.

Shared services and platforms:

  • Administer shared services (e.g. DNS, NTP, SMTP relays, web servers, file servers).
  • Support application teams using the shared Linux infrastructure.
  • Maintain and optimize virtualization and/or container platforms (VMware, KVM, Docker, Kubernetes – depending on the environment).
  • Contribute to standardizing environments and configurations across multiple teams.

Monitoring, incident management, and on-call:

  • Configure and maintain monitoring and alerting tools (e.g. Zabbix, Prometheus, Nagios, Grafana).
  • Investigate and resolve incidents affecting shared systems and services.

Participate in a rotating on-call duty schedule (24/7 support):

  • Respond to alerts within defined SLAs.
  • Perform first analysis, mitigation, and escalation when needed.
  • Communicate clearly with stakeholders during major incidents.
  • Contribute to post-incident reviews (RCA) and continuous improvement actions.

Security and compliance:

  • Apply security best practices and hardening guidelines on Linux systems.
  • Work with security teams to identify, prioritize, and remediate vulnerabilities.
  • Manage firewalls, VPN access, and secure remote access (SSH, bastion/jump hosts).
  • Ensure compliance with internal policies and external regulations where applicable.

Backup, recovery, and continuity:

  • Regularly test recovery and disaster scenarios.
  • Help define and meet RPO/RTO targets for critical services.

Automation and industrialization:

  • Use scripting (Bash, Python, etc.) to automate recurring operational tasks.
  • Use configuration management tools (e.g. Ansible, Puppet, Chef, SaltStack) to maintain consistent environments.
  • Contribute to infrastructure as code and standard operating procedures.

Documentation and collaboration:

  • Create and maintain clear technical documentation, runbooks, and on-call procedures.
  • Collaborate closely with application, network, security, and other support teams.
  • Share knowledge within the team and help onboard new colleagues.
  • Participate actively in team meetings, capacity reviews, and planning sessions.

Profile

  • 3–5 years of Linux administration in operations/run environments.
  • Strong troubleshooting, communication, and teamwork skills.
  • Fluent in English; able to work under on‑call conditions.

Technical Skills

  • Linux administration (Ubuntu/Debian/CentOS/RHEL).
  • System setup, configuration, hardening, users & permissions, SSH, packages.
  • Networking basics (TCP/IP, DNS, routing, firewall).
  • Web servers (Apache, Nginx) & log management.
  • Monitoring (Zabbix/Prometheus/Nagios), backups, Bash scripting.
  • Production troubleshooting and performance diagnostics.

Nice-to-Have

  • Virtualization (VMware/KVM), Docker/Kubernetes.
  • Ansible/Puppet/Chef/SaltStack; Terraform/CloudFormation.
  • AWS/Azure/GCP; CI/CD tools.
  • Knowledge of security frameworks (CIS/ISO/NIST).

Soft Skills

  • High sense of responsibility; calm under pressure.
  • Clear communication with technical & non-technical teams.
  • Organized, structured, and improvement‑oriented.

On-Call

  • Participation in rotating on‑call schedules.
  • Fast alert response & remote troubleshooting.

 

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    Linux System Administrator at Inetum | Renata