Senior System Administrator Job Mississauga area,Ontario Canada,IT/Tech

Overview

At OSL Retail Services, we believe people are the heart of everything we do, and it is an exciting time to be part of something special! Our momentum is growing, and is fueled by innovation, collaboration, and a shared entrepreneurial spirit that drives real results. Founded in 2012 in Mississauga, Ontario, OSL delivers customized sales solutions in retail, direct sales, and customer acquisition, all built on a foundation of integrity, respect, and passion.

Our culture thrives on connection, purpose, and growth. If you’re looking for a place where your talents are valued, your ideas matter, and your career can grow, we’d love to meet you.

The Opportunity:

We are recruiting a Senior System Administrator
. Reporting to the VP IT, in this role, you will be instrumental in managing our corporate infrastructure, cybersecurity and cloud services. Your expertise will ensure the highest reliability and performance, supporting our commitment to delivering exceptional service to our clients and customers. This role involves working on complex projects, including evolving existing systems and implementing new technologies. It will be based out of our corporate office in Mississauga, Ontario.

What You’ll Do:

Oversee corporate network operations: Administer network infrastructure, firewalls, VPNs, and maintain robust network troubleshooting and security measures.

Develop and maintain documentation: Prepare and update system configurations, mappings, process documentation, and problem management records.

Supervise desktop and cloud infrastructure: Manage both on-premises and Azure cloud environments.

Continually monitor OSL’s IT landscape: Maintain vigilant oversight of capacity and performance metrics.

Support IT strategy and service improvement: Actively participate in tactical planning and contribute to the enhancement of all IT service deliveries.

Administer application servers: Oversee a diverse environment comprising Windows, Linux, and Azure-based resources.

Enforce security controls: Ensure the implementation of best-practice security measures across all systems.

Required Knowledge, Skills, and Abilities:

Deep expertise in designing, operating, and securing enterprise network environments, including firewalls, switches, access points, VPN technologies, and MPLS or equivalent WAN solutions.

Strong systems engineering background with advanced experience in automation, configuration management, and secure-by-design principles across network and infrastructure platforms.

Demonstrated ability to lead the technical design and implementation of complex networking and security initiatives, balancing scalability, resiliency, and risk management.

Advanced proficiency administering and troubleshooting both Windows and Linux environments, with the ability to diagnose and resolve issues across networking, systems, and applications.

Extensive experience with scripting and automation using Power Shell, Bash, and/or Python to improve reliability, reduce manual effort, and enforce standards.

Hands-on experience building and operating monitoring, observability, and alerting solutions using tools such as Zabbix, Azure Monitor, Prometheus, Grafana, Datadog, and centralized logging platforms (., ELK, Loki, Graylog).

Strong working knowledge of Microsoft Entra / Active Directory, identity federation, and access control models in hybrid and cloud-integrated environments.

Proven ability to take full ownership of technical outcomes, including architecture decisions, implementation, documentation, and ongoing operational excellence.

Excellent communication and stakeholder management skills, with the ability to translate complex technical concepts, risks, and trade-offs into clear business-facing language.

Experience providing Tier‑3 operational support and participating in after-hours on-call rotations for critical infrastructure services.

Solid understanding of ITIL practices (Incident, Change, and Problem Management), with experience improving operational processes and system stability over time.

What you’ve done:

5+ years of experience supporting engineering enterprise environments across networking, security, Windows and Linux…