Collect and interpret logs (for example, VPC Flow Logs, ELB access logs, AWS WAF web ACL logs, CloudFront logs).

VPC Flow Logs record information about the IP traffic going to and from network interfaces in your VPC. To collect VPC Flow Logs, you need to create a flow log for a VPC, subnet, or network interface.

To enable VPC Flow Logs, use the following steps:

1. Navigate to the VPC console.
2. Select the VPC, subnet, or network interface.
3. Choose “Create flow log” and specify the necessary details, such as the destination log group in CloudWatch Logs or an S3 bucket.

Once enabled, the flow logs capture information such as the source and destination IP addresses, port numbers, protocol, and whether the traffic was accepted or rejected. These logs are useful for network troubleshooting and security analysis.

ELB Access Logs

ELB Access Logs contain detailed information about requests sent to the load balancer. Enabling them helps you understand the nature of the traffic and troubleshoot application issues.

To enable ELB Access Logs:

1. Open the Amazon EC2 console.
2. Navigate to the Load Balancers section.
3. Select the ELB and go to the “Attributes” tab.
4. Find “Access logs” and click on “Edit.” Enable the logs and set the S3 destination for the logs.

The logs contain data such as client IP addresses, request paths, server responses, and request processing times.

AWS WAF Web ACL Logs

AWS WAF Web ACL Logs capture the details of incoming web requests that AWS WAF processes. They’re useful for identifying and understanding web attack patterns.

To enable AWS WAF logs:

1. Go to the AWS WAF & Shield console.
2. Select the corresponding Web ACL.
3. Enable logging under the “AWS WAF logs” option. Specify the Amazon Kinesis Data Firehose, which will deliver the logs to an S3 bucket or CloudWatch Logs.

These logs consist of HTTP(S) request details, such as the IP address, URI, headers, and the rule that the request matched.

CloudFront Logs

CloudFront provides two types of logs: access logs (standard logs) and real-time logs. Access logs are useful for in-depth analysis, whereas real-time logs are beneficial for immediate access to data.

To enable standard access logs:

1. Navigate to the CloudFront console.
2. Choose the distribution and go to the “Distribution Settings.”
3. Select the “Logs” tab and update the settings, specifying an S3 bucket for the logs.

CloudFront logs include the requester’s IP address, request URLs, HTTP status codes, and edge location details.

Interpreting Logs

Once you have collected these logs, you need to interpret them to gain insights. AWS provides several tools for this purpose:

• Amazon CloudWatch Logs Insights: For querying and visualizing log data.
• Amazon Athena: For running SQL queries on logs stored in S3.
• Third-party tools: Like Splunk or Sumo Logic, integrated with AWS for log analysis.

For example, with Amazon Athena you could run a query on your VPC Flow Logs to find the volume of rejected traffic over the last 24 hours:

SELECT
interface_id,
srcaddr,
dstaddr,
count(*) as request_count
FROM
“your_flow_logs_database”.”your_flow_logs_table”
WHERE
action=’REJECT’ AND
parse_datetime(timestamp, ‘yyyy-MM-dd”T”HH:mm:ss.SSS’) > date_add(‘day’, -1, now())
GROUP BY
interface_id, srcaddr, dstaddr
ORDER BY
request_count DESC;

Parsing and interpreting logs effectively enable SysOps Administrators to maintain the performance, security, and reliability of AWS environments. There are also AWS certification-specific questions that will test your knowledge on how to enable and interpret the different types of logs provided by AWS. Understanding the format and the kind of data each type of log contains is critical for the AWS Certified SysOps Administrator – Associate exam.