Encapsulation and encryption technologies (for example, Generic Routing Encapsulation [GRE], IPsec)

Can you explain what Generic Routing Encapsulation (GRE) is and when you would use it in AWS?

GRE is a tunneling protocol developed by Cisco that encapsulates a wide variety of protocol packet types inside IP tunnels, creating a virtual point-to-point link to various brands of routers at remote points over an internetwork. In AWS, you might use GRE to facilitate the encapsulation of protocols that are not supported natively over AWS Direct Connect or a VPN connection, such as multicast or non-IP traffic.

What is the difference between GRE and IPsec VPN, and why would you choose one over the other when connecting to AWS?

GRE is an encapsulation protocol that can tunnel different network layer protocols, but it doesn’t provide encryption or confidentiality by itself. IPsec VPN, on the other hand, not only encapsulates traffic but also provides secure encryption, ensuring that data remains confidential and is only accessible to authenticated parties. You would choose GRE when you need to encapsulate protocols that IPsec does not support, and IPsec when security and data protection are primary concerns.

In AWS, how does IPsec help secure data-in-transit?

IPsec (Internet Protocol Security) is a suite of protocols used to secure Internet Protocol (IP) communications by authenticating and encrypting each IP packet in a data stream. In AWS, IPsec is employed in Virtual Private Networks (VPNs) to create a secure tunnel over the internet between a customer’s data center and the AWS environment, ensuring confidentiality, integrity, and authenticity of the data-in-transit.

What is the significance of the Security Association (SA) in an IPsec connection, and how do SAs affect network performance?

A Security Association (SA) is a logical relationship established between two IPsec peers that describes the configurations required to secure traffic between them. SAs define the protocols and algorithms used to secure traffic in an IPsec session. They impact network performance by determining how much overhead is added to the packets during encryption and decryption processes. The choice of encryption and hashing algorithms can significantly affect the speed of the secure communication.

What are the two modes of IPsec operation, and which mode would you typically use in a site-to-site VPN scenario?

The two modes of IPsec operation are Transport Mode and Tunnel Mode. Transport Mode encrypts only the payload of each packet, while Tunnel Mode encrypts both the header and the payload. In a site-to-site VPN scenario, Tunnel Mode is typically used because it encapsulates the entire IP packet, allowing for secure communication between two different networks.

Can you describe the two phases of IKE (Internet Key Exchange) used in setting up an IPsec connection, and the purpose of each phase?

IKE operates in two phases. Phase 1 establishes the initial secure channel between the two peers, authenticating the peers and setting up a secure, encrypted channel by negotiating cryptographic parameters used to protect this channel. Phase 2 uses the secure channel established in Phase 1 to negotiate Security Associations that are applied to the actual IPsec tunnel for encrypting the data traffic.

In the context of AWS VPN, what are the advantages of implementing AWS Client VPN?

AWS Client VPN allows for secure connections to AWS or on-premises networks from any location using OpenVPN-based clients. It offers the advantages of being managed, highly available, and elastic, scaling the number of connections up or down based on demand. It also integrates with AWS Directory Service for authentication and authorization, enabling fine-grained access control.

What role does the AWS Virtual Private Gateway (VGW) play in the establishment of an IPsec VPN connection?

The AWS Virtual Private Gateway (VGW) is the side of the VPN connection that is attached to your VPC. It serves as the endpoint for the IPsec VPN connection and is responsible for managing the IPsec tunnels, handling encryption and decryption, and routing traffic between your on-premises environment and your VPC.

How do Diffie-Hellman groups factor into the strength of an IPsec VPN connection, and which groups are currently recommended for strong security?

Diffie-Hellman groups determine the size and strength of the key used in the key exchange process within IPsec. Stronger groups with larger prime numbers offer stronger security but may require more computational power. Currently, groups like 14, 19, 20, 24, which provide 2048-bit and stronger key strengths, are recommended for strong security.

Can you explain the difference between policy-based and route-based VPNs, and how these configurations might differ on AWS?

Policy-based VPNs trigger the tunnel based on match criteria defined in the VPN policies, which typically involve specific source and destination IP addresses. In contrast, route-based VPNs use routing tables and can support dynamic routing protocols such as BGP. AWS supports route-based VPN configurations, which is beneficial for applications that require dynamic routing over the VPN tunnel.