What is a Security List in OCI?

A Security List in Oracle Cloud Infrastructure (OCI) acts as a virtual firewall that governs the inbound and outbound traffic for the subnets in a Virtual Cloud Network (VCN). It comprises a set of rules that define which traffic is allowed or denied based on various parameters such as IP address, port number, and protocol type.

When a resource, such as an instance, is associated with a subnet, the Security List attached to that subnet applies to the network traffic associated with that resource. This functionality is critical for maintaining network security and ensuring that only authorized traffic reaches or leaves the resources within the VCN.

The features provided by Security Lists allow for fine-tuning of traffic management, facilitating secure application interactions, and enhancing overall network security posture in the cloud environment.