Creating and analyzing network traffic mirroring (for example, using VPC Traffic Mirroring)

Can you describe what VPC Traffic Mirroring is and provide a general use case for this feature?

VPC Traffic Mirroring is an AWS feature that allows you to copy network traffic from an elastic network interface (ENI) of an EC2 instance within a VPC and forward it to a security appliance or a monitoring instance. A general use case is for content inspection, intrusion detection, and troubleshooting network issues without affecting production traffic.

What types of traffic can you mirror using VPC Traffic Mirroring?

VPC Traffic Mirroring can mirror all ingress and egress traffic, including TCP, UDP, and ICMP traffic, along with the associated metadata from the network interface of an EC2 instance to a target destination for analysis.

How do you set up a Traffic Mirroring session in AWS?

To set up a Traffic Mirroring session, you first need to create a Traffic Mirror Target (like an EC2 instance or a Network Load Balancer), a Traffic Mirror Filter that defines the rules for what traffic to mirror, and then create a Traffic Mirroring Session to tie the interface, target, and filter together.

What are the limitations to be aware of when implementing VPC Traffic Mirroring?

Some limitations include: it is available only for instances with the Nitro System, you cannot mirror traffic to a different VPC than the source, there is a maximum of three sessions per ENI, and there is no support for mirroring traffic within the same EC2 instance (instance-to-instance).

Can you mirror traffic to a destination outside of the AWS environment, such as an on-premises data center?

VPC Traffic Mirroring does not support sending traffic directly to an external on-premises data center. However, you can send mirrored traffic to an ENI or a Network Load Balancer that forwards the traffic to an on-premises location via a VPN or Direct Connect.

What is the role of a Traffic Mirror Filter, and how does it work?

A Traffic Mirror Filter defines the rules for which traffic to capture, based on specific criteria such as protocol, port range, and source/destination IP address. Traffic that matches the filter criteria is forwarded to the Traffic Mirror Target; non-matching traffic is not mirrored.

How does AWS ensure the security of mirrored traffic?

Traffic is mirrored within the AWS network infrastructure, enforcing the same security measures as typical VPC traffic. However, the security of the mirrored traffic is also the responsibility of the user; they must secure the ENI or Network Load Balancer receiving the mirrored traffic. AWS also recommends using encryption if the traffic is being forwarded out of the AWS environment.

Are there any considerations to take into account regarding the performance impact of traffic mirroring on the source instances?

While VPC Traffic Mirroring is designed to be non-disruptive, there is some additional overhead on the source instance for copying the traffic. It’s important to monitor performance and ensure the instance has adequate bandwidth and CPU resources to handle the additional load without impacting application performance.

How can you analyze the data collected from Traffic Mirroring?

The data collected from Traffic Mirroring can be analyzed using network monitoring and security analysis tools such as intrusion detection systems (IDS) or network traffic analysis software that can ingest and interpret the mirrored traffic.

What is the difference between VPC Flow Logs and VPC Traffic Mirroring?

VPC Flow Logs capture information about IP traffic going to and from network interfaces in VPCs. They provide a record of the communication between hosts within the VPC, but not actual packets or payloads. On the other hand, VPC Traffic Mirroring copies the actual traffic and provides full packet-level data for in-depth analysis.

Can you explain how to control the data volume in a Traffic Mirroring session?

You can control the data volume by properly defining the Traffic Mirror Filter rules to include only the specific traffic you are interested in. Additionally, you can use sampling to reduce the volume by mirroring only a percentage of the traffic.

If a network interface is attached to multiple EC2 instances through Elastic Network Interface (ENI) attachments, how can traffic mirroring be managed?

For a network interface that is attached to multiple instances (multihomed instances), traffic mirroring needs to be configured separately for each ENI. You must create an individual Traffic Mirror Session for each ENI you want to capture traffic from since each ENI behaves as an independent network interface.