Cybersecurity is vital in our world that uses the public Internet to communicate in every field of activity. In this paper, we present a concise overview of a Security Operation Center (SOC) implementation that combines open source components and operates as a service (SOCaaS). The focus is on the case study of Security Onion, an open source security-monitoring platform, to highlight the effectiveness of this approach. The paper highlights the architecture, key features, and benefits of the SOCaaS model with open source components, emphasizing the integration of Security Onion’s intrusion detection, network security monitoring, and log management capabilities. The case study demonstrates the practicality and scalability of Security Onion within the SOCaaS framework. It also addresses challenges and considerations, such as resource requirements, skill gaps, and data privacy. The paper offers insights into how organizations can leverage open source tools like Security Onion to enhance security operations while maintaining control and optimizing costs.