The ELK stack is a set of analytics tools. Its initials represent Elasticsearch, Logstash and Kibana. Elasticsearch is a flexible and powerful open source, distributed, real-time search and analytics engine. Logstash is a tool for receiving, processing and outputting logs, like system logs, webserver logs, error logs, application logs and many more. Kibana is an open source (Apache-licensed), browser-based analytics and search dashboard for Elasticsearch.
more here.........http://blogs.cisco.com/security/step-by-step-setup-of-elk-for-netflow-analytics
more here.........http://blogs.cisco.com/security/step-by-step-setup-of-elk-for-netflow-analytics