Scope and fit
Security Onion is a Linux distribution for security monitoring, threat hunting, and log management. It brings together tools and workflows for examining network and host telemetry, so a useful deployment begins with a clear picture of the traffic and data your team needs to investigate.
A platform for investigation
Security Onion provides an integrated environment for collecting and reviewing security telemetry. Teams can use it to search events, inspect network activity, and organize investigation workflows across supported deployments.
Choose the right visibility points
The value of a sensor depends on what it can observe. Before deployment, identify network tap or mirror sources, monitored segments, endpoint or log integrations, and the access analysts need to the resulting data.
Make operations sustainable
Retention, storage throughput, update planning, and analyst coverage affect how well the platform works over time. A runbook should cover sensor health, data gaps, escalation, backups, and the process for maintaining the supported Security Onion release.
Decisions and tradeoffs
Use this table as a working review record. Replace assumptions with evidence from the target environment.
| Decision area | Working guidance |
|---|---|
| A platform for investigation | Security Onion provides an integrated environment for collecting and reviewing security telemetry. Teams can use it to search events, inspect network activity, and organize investigation workflows across supported deployments. |
| Choose the right visibility points | The value of a sensor depends on what it can observe. Before deployment, identify network tap or mirror sources, monitored segments, endpoint or log integrations, and the access analysts need to the resulting data. |
| Make operations sustainable | Retention, storage throughput, update planning, and analyst coverage affect how well the platform works over time. A runbook should cover sensor health, data gaps, escalation, backups, and the process for maintaining the supported Security Onion release. |
Implementation questions
What should the team decide about a platform for investigation?
Security Onion provides an integrated environment for collecting and reviewing security telemetry. Teams can use it to search events, inspect network activity, and organize investigation workflows across supported deployments. Use a named owner and a written acceptance check so this decision can be reviewed after deployment.
What should the team decide about choose the right visibility points?
The value of a sensor depends on what it can observe. Before deployment, identify network tap or mirror sources, monitored segments, endpoint or log integrations, and the access analysts need to the resulting data. Use a named owner and a written acceptance check so this decision can be reviewed after deployment.
What should the team decide about make operations sustainable?
Retention, storage throughput, update planning, and analyst coverage affect how well the platform works over time. A runbook should cover sensor health, data gaps, escalation, backups, and the process for maintaining the supported Security Onion release. Use a named owner and a written acceptance check so this decision can be reviewed after deployment.
Plan, build, verify, operate
A platform for investigation: Security Onion provides an integrated environment for collecting and reviewing security telemetry. Teams can use it to search events, inspect network activity, and organize investigation workflows across supported deployments. Record the result and the next owner before changing the next boundary.
Choose the right visibility points: The value of a sensor depends on what it can observe. Before deployment, identify network tap or mirror sources, monitored segments, endpoint or log integrations, and the access analysts need to the resulting data. Record the result and the next owner before changing the next boundary.
Make operations sustainable: Retention, storage throughput, update planning, and analyst coverage affect how well the platform works over time. A runbook should cover sensor health, data gaps, escalation, backups, and the process for maintaining the supported Security Onion release. Record the result and the next owner before changing the next boundary.
Deployment checks
Turn the page into a reviewable handover by assigning each check to a person and retaining its result.
Network security monitoring
A platform for investigation: Network security monitoring. Confirm the owner, input, evidence, and acceptance check before this work moves into production.
Threat hunting and event search
A platform for investigation: Threat hunting and event search. Confirm the owner, input, evidence, and acceptance check before this work moves into production.
Analyst workflows for investigations
A platform for investigation: Analyst workflows for investigations. Confirm the owner, input, evidence, and acceptance check before this work moves into production.
Prioritize high-value network segments
Choose the right visibility points: Prioritize high-value network segments. Confirm the owner, input, evidence, and acceptance check before this work moves into production.
Validate traffic mirroring and sensor capacity
Choose the right visibility points: Validate traffic mirroring and sensor capacity. Confirm the owner, input, evidence, and acceptance check before this work moves into production.
Define who can access sensitive telemetry
Choose the right visibility points: Define who can access sensitive telemetry. Confirm the owner, input, evidence, and acceptance check before this work moves into production.
Sensor placement and evidence
Security Onion is most useful when the collection point has a clear question behind it. A sensor watching an internet edge, a data-centre boundary, or a sensitive internal segment sees different traffic and needs a different retention decision. Draw the traffic path before provisioning a sensor. Identify the tap or switch mirror source, the direction of traffic, VLAN handling, expected encrypted traffic, and whether the copy can drop packets under load.
Validate visibility with controlled checks. Confirm that expected traffic reaches the capture interface, that timestamps make sense, and that the system can retain the related network metadata and logs long enough for the intended investigation window. Packet capture, network metadata, IDS alerts, endpoint data, and external logs answer different questions. Do not describe one as a substitute for another.
Security Onion combines tools and workflows for network security monitoring and investigation, but it still needs analysts to define a triage path. Specify which detections create a case, who can inspect sensitive packet data, what evidence may leave the environment, and when a network or infrastructure owner is called. Search access is an access-to-telemetry decision, not merely a dashboard role.
Storage planning must include the data types actually retained. Full packet capture has very different growth from alerts or metadata. Measure a pilot on a representative observation point, account for maintenance headroom, and set an explicit response when capacity is approached. A sensor that silently loses its mirror feed or a storage pool that fills during an incident creates false confidence.
The handover pack should include the network diagram, approved sensor locations, retention schedule, analyst roles, health checks, and recovery steps for manager and sensor nodes. Exercise an investigation from a known event through search, supporting network evidence, escalation, and case closure before calling the service ready.
Handover and ownership
Before handover, name the system owner, support path, access boundary, backup or recovery responsibility, and the condition that pauses a change.
Keep a short record of what was tested, what remains outside scope, and when the review should happen again.
