Network ACL Usage Guidelines

Here are some common network ACL configuration examples, including controlling external access to instances in a subnet, and controlling network communications or isolation between subnets.

• Controlling External Access to Instances in a Subnet
• Controlling Communications Between Instances in Different Subnets
• Denying External Access to a Specific Port in a Subnet
• Denying Access from a Specific IP Address
• Allowing External Access to Specific Ports on an Instance in a Subnet

• Does a New Security Group Rule or Network ACL Rule Take Effect Immediately for Existing Connections?
• Why Is Access from a Specific IP Address Still Allowed After a Network ACL Rule That Denies the Access from the IP Address Has Been Added?
• Why Is Outbound Access on TCP Port 25 Blocked?