Update Network ACL

Update Network ACL

ℹ️ Information: Network ACLs provide an additional layer of security for your VPC, acting as a stateless firewall at the subnet level. In this section, you will configure Network ACLs to control traffic between VPCs.

💡 Pro Tip: Network ACLs are evaluated in order, starting with the lowest numbered rule. The first rule that matches the traffic is applied, regardless of any subsequent rules.

Implementation Steps

  1. Access AWS Management Console
    • Search for VPC
    • Select VPC service

VPC Console

  1. Navigate to Network ACLs
    • Select Network ACLs from the left sidebar
    • Select the Network ACL associated with HG VPC subnets
    • Click the Inbound Rules tab
    • Click Edit inbound rules

Network ACL Configuration

  1. Modify Rule 100
    • Change Source from 0.0.0.0/0 to 172.31.0.0/16
    • Click Save changes

Update Network ACL Rule

  1. Verify Configuration
    • Network ACL now only allows traffic from My VPC CIDR block
    • Only IP addresses in the 172.31.0.0/16 range can connect to HG VPC subnets

Network ACL Verification

  1. Test Configuration
    • From your terminal, attempt to ping the public IP of EC2 - HG VPC
    • The ping should fail as the Network ACL now restricts internet access

Network ACL Test

🔒 Security Note: Network ACLs provide an additional layer of security by controlling traffic at the subnet level. They are stateless, meaning you must configure both inbound and outbound rules.

⚠️ Warning: Be careful when modifying Network ACL rules in production environments. Incorrect configurations can disrupt network connectivity.

💡 Pro Tip: Consider documenting your Network ACL rules and their purposes to maintain clear security policies and facilitate troubleshooting.