Securing Your AWS Resources within the VPC with NACLs and Security Groups

While IGWs and NAT gateways facilitate connectivity to other networks from the VPC, you will still need to configure necessary firewall rules to determine what type of traffic is allowed, both inbound and outbound.

AWS VPCs can be configured with two firewall options: security groups and NACLs, as well as virtual appliances from vendors who have software versions of their products in AWS Marketplace that work on either bring-your-own-license (BYOL) or pay-as-you-go pricing models. Let us look at security groups next.

Security Groups

Security groups are a firewall solution that you create and then attach directly to a resource such as an EC2 instance. You can configure security group rules to allow traffic to and from the resource and define what ports and protocols will be permitted. You configure security groups by creating or removing rules. When defining your rules, you need to specify the source...