Download ELK related components
-the official website of elk can not be opened frequently. Record the following url for this purpose. Change the version number according to the required version and download it.
-https://artifacts.elastic.co/downloads/kibana/kibana-6.7.2-linux-x86_64.tar.gz
-https://artifacts.elastic.co/downloads/beats/filebeat/filebeat-6.7.2-linux-x86_64.tar.gz
-https://artifacts.elastic.co/downloads/logstash/logstash-6.7.2.tar.gz
-https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.7.2.tar.gz
