Network ACLs
Network Access Control Lists (ACLs) are stateless, rule-based security filters that operate at the subnet level in cloud and network environments to control inbound and outbound traffic. They function as a firewall for subnets, allowing or denying traffic based on rules defined by source/destination IP addresses, ports, and protocols. Unlike security groups, which are stateful and apply to instances, Network ACLs are stateless and evaluate traffic in both directions independently.
Developers should learn Network ACLs when designing secure cloud architectures, particularly in AWS, Azure, or other cloud platforms, to enforce network segmentation and compliance requirements. They are essential for scenarios like isolating public and private subnets, blocking malicious IP ranges, or implementing layered security alongside security groups. Use them for coarse-grained traffic control at the subnet level, such as in VPCs, to add an extra layer of defense against unauthorized access.