What is NACL?


NACL stands for Network Access Control List, and it adds a layer of security to the Amazon Web Services stack.

NACL aids in the provision of a firewall, thereby assisting in the security of VPCs and subnets. It contributes to the establishment of a security layer that controls and manages the traffic that moves between subnets. It is an optional layer for VPC that adds another security layer to the Amazon service.

VPC is an abbreviation for Virtual Private Cloud, which can be thought of as a container that stores subnets. Subnets can be thought of as a container that aids in the storage of data. 

NACL Components

The following are the Network Access Control List (NACL) components:

  • Rule number: Each rule is given a unique number. The priority of the rule is also determined by the number assigned to it. This rule is applied to a request when it corresponds to a specific request or traffic, regardless of whether another high-numbered rule contradicts it or not.

Rules are created with specific increments, such as the difference between two rules being either 1, 10, or 100, and this difference is shared by all rules created.

NACL is available in two forms:

  1. Customized NACL: Also known as a user-defined NACL, it has the inherent property of denying all incoming and outgoing traffic until a rule to handle the traffic is added.
  2. Default NACL: This is the inverse of customized NACL, allowing all network traffic to flow in and out. It also includes a specific rule that has a rule number and cannot be changed or deleted. Access to the request is denied if it does not comply with the associated rule. Changes to the subnets associated with a rule are automatically applied when it is added or removed.

Groups for Security

Security Groups and Their Role

Every Security Group, like a firewall, has a set of rules that filter traffic entering and leaving the EC2 instances. As previously stated, security groups are associated with EC2 instances and provide port and protocol access protection. Normally, the firewall has a ‘Deny rule,’ but the SG has a “Deny All” setting that allows data packets to be dropped if no rule is assigned to them from the source IP.

In addition, when compared to a Network Access Control List (NACL), security groups form the first layer of defence at the instance level in a cloud computing environment, whereas NACLs provide a second layer of protection at the subnet level.

When creating a security group, each group will be assigned to a specific virtual private cloud VPC. It’s also a good idea to give each group a name and description for easy access from the account menus. It’s also worth noting that when you create a security group, make sure it’s assigned to the VPC it’s supposed to protect to avoid mistakes.

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