Deploy an ExtraHop Flow Sensor with AWS

Collecting flow logs requires the following configuration setup.

1. Configure an IAM policy and IAM role.
2. Deploy the ExtraHop flow sensor instance in AWS.
3. Download and configure an ExtraHop-supplied Lambda function. The Lambda function runs whenever new flow logs become available and then relays any new events to your sensor. See the following AWS documentation for more information: Using Lambda with CloudWatch Logs.
4. Enable VPC Flow Logs publishing for a set of VPCs in your environment.
5. Add a Lambda trigger.
6. Configure Route 53.

1. Create an IAM policy through the JSON tab with the following parameters:

   {
       "Statement": [
           {
               "Action": [
                   "ec2:Describe*"
               ],
               "Effect": "Allow",
               "Resource": "*"
           }
       ],
       "Version": "2012-10-17"
   }
   

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2. Create an IAM role and attach the permission policy.
   The ExtraHop system requires an instance IAM role to correlate IP addresses from flow logs to instances, gateways, and Lambdas.

1. Deploy a Reveal(x) EDA 1100V by following the Deploy an ExtraHop sensor in AWS guide.
   The EDA 1100V is a packet sensor that becomes a flow logs sensor when the license is entered. The sensor will no longer process packets.

   Tip:	You can subscribe to the Reveal(x) 1100v (BYOL) software through the AWS Marketplace.

2. After the instance is created and running, attach the IAM role you created above.
3. Log in to the ExtraHop system through https://<extrahop-hostname-or-IP-address>. The username is setup and the password is the string of numbers after the i- in the instance ID.
4. Follow the prompts to accept the license agreement, enter the product key, change the default setup and shell user account passwords, connect to ExtraHop Cloud Services, and connect to Reveal(x) 360.
5. Click the System Settings icon , and then click All Administration.
6. In the Access Settings section, click API Access.
7. In the Generate an API Key section, type a description for the new key and then click Generate.
8. Generate the Flow Log secret from the REST API Explorer.
   1. Click Open ExtraHop API Explorer.
   2. Click Enter API Key and then paste or type your API key into the API Key field.
   3. Click Authorize and then click Close.
   4. Click ExtraHop and then click POST ​/extrahop​/flowlogs​/secret.
   5. Click Try it out and then click Send Request.
   6. In the Response Body section, view and record the secret value. You will need the secret for the EXTRAHOP_SECRET_KEY environment variable in the next procedure.

An ExtraHop-supplied lambda function routes new flow log events to the ExtraHop flow sensor whenever called by a CloudWatch lambda trigger.

1. Download the exflowlogs-lambda.zip file from the ExtraHop downloads page.
2. In AWS, create a Lambda function.
   • The function must have the Go1.x runtime.
   • The function must have an execution role with the following permissions:

     CloudWatch Logs:

     • CreateLogGroup
     • CreateLogStream
     • PutLogEvents

     EC2:

     • CreateNetworkInterface
     • DeleteNetworkInterface
     • DescribeNetworkInterfaces

   • You must enable connectivity between your Lambda function and the VPC and subnet that your collector is on. The function must also be part of a security group that allows traffic between the function and collector.
   • Upload the exflowlogs-lambda.zip file.
   • Under General configuration settings, set the Memory field to 128 MB.
   • Under General configuration settings, set the Timeout field to 10 seconds.
   • Under Code, Runtime settings, set the handler value to exflowlogs-lambda.
   • In the Environment variables settings, set the following environment variables:

     EDA_HOST: The IP address or hostname of the VPC flow logs sensor.

     EXTRAHOP_SECRET_KEY: The secret you generated through the ExtraHop REST API in the previous procedure.

     VERIFY_EDA_HOST_CERT: If the sensor has the default self-signed certificate, specify 0 to disable certificate verification in the Lambda HTTP client. Otherwise, specify 1.

   Note:

   It can take up to 10 minutes before devices are discovered and metrics are published from flow logs.

1. Identify the VPCs that you want to monitor with the flow sensor.
   • If your ExtraHop AWS deployment includes packet sensors, you should avoid monitoring a particular VPC with both a packet sensor and a flow logs sensor.
   • While it is possible to send logs for smaller units like individual subnets or interfaces, sending the entire VPC yields the best discovery of devices.
2. Create a CloudWatch log group to receive the flow logs.
3. Create an IAM policy through the JSON tab with the following statement:

   {
     "Version": "2012-10-17",
     "Statement": [
       {
         "Action": [
           "logs:CreateLogGroup",
           "logs:CreateLogStream",
           "logs:PutLogEvents",
           "logs:DescribeLogGroups",
           "logs:DescribeLogStreams"
         ],
         "Effect": "Allow",
         "Resource": "*"
       }
     ]
   }  
   

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4. Identify an existing IAM role or create a new IAM role with a custom trust policy that allows Amazon EC2 to publish flow logs to a CloudWatch log group. The custom trust policy must have the following statement:

   {
     "Version": "2012-10-17",
     "Statement": [
       {
         "Effect": "Allow",
         "Principal": {
           "Service": "vpc-flow-logs.amazonaws.com"
         },
         "Action": "sts:AssumeRole"
       }
     ]
   }
   

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5. Add the permission policy you created in step 3 to the role.
6. Configure how VPC flow logs are sent to the CloudWatch group. The ExtraHop system requires the following configuration:

   Filter: Accept

   Maximum aggregation interval: 1 Minute

   Custom log format: You must select the attributes in the following order:

   • end
   • log-status
   • vpc-id
   • interface-id
   • srcaddr
   • dstaddr
   • srcport
   • dstport
   • protocol
   • tcp-flags
   • packets
   • bytes
   • pkt-srcaddr
   • pkt-dstaddr

   The format preview should appear similar to the following figure.