network ACL (NACL)

An optional layer of security that acts as a firewall for controlling traffic in and out of a subnet. You can associate multiple subnets with a single network ACL, but a subnet can be associated with only one network ACL at a time.

Resources

https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_ACLs.html