How to do it…

To setup the networking, use the following steps:

Using a standard Elasticsearch configuration config/elasticsearch.yml file, your node will be configured to bind on the localhost interface (by default) so that it can't be accessed by external machines or nodes.
To allow another machine to connect to our node, we need to set network.host to our IP (for example, I have 192.168.1.164).
To be able to discover other nodes, we need to list them in the discovery.zen.ping.unicast.hosts parameter. This means that it sends signals to the machine in a unicast list and waits for a response. If a node responds to it, they can join in a cluster.

In general, from Elasticsearch version 6.x, the node versions are compatible. You must have the same cluster name (the cluster.name option in elasticsearch.yml) to let nodes join with each other.

The best practice is to have all the nodes installed with the same Elasticsearch version (major.minor.release). This suggestion is also valid for third-party plugins.

To customize the network preferences, you need to change some parameters in the elasticsearch.yml file, as follows:

cluster.name: ESCookBook
node.name: "Node1"
network.host: 192.168.1.164
discovery.zen.ping.unicast.hosts: ["192.168.1.164","192.168.1.165[9300-9400]"]

This configuration sets the cluster name to Elasticsearch, the node name, the network address, and it tries to bind the node to the address given in the discovery section by performing the following tasks:

- We can check the configuration during node loading
- We can now start the server and check whether the networking is configured, as follows:

[2018-10-28T17:42:16,386][INFO ][o.e.c.s.MasterService ] [Node1] zen-disco-elected-as-master ([0] nodes joined)[, ], reason: new_master {Node1}{fyBySLMcR3uqKiYC32P5Sg}{IX1wpA01QSKkruZeSRPlFg}{192.168.1.164}{192.168.1.164:9300}{ml.machine_memory=17179869184, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true}
 [2018-10-28T17:42:16,390][INFO ][o.e.c.s.ClusterApplierService] [Node1] new_master {Node1}{fyBySLMcR3uqKiYC32P5Sg}{IX1wpA01QSKkruZeSRPlFg}{192.168.1.164}{192.168.1.164:9300}{ml.machine_memory=17179869184, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true}, reason: apply cluster state (from master [master {Node1}{fyBySLMcR3uqKiYC32P5Sg}{IX1wpA01QSKkruZeSRPlFg}{192.168.1.164}{192.168.1.164:9300}{ml.machine_memory=17179869184, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true} committed version [1] source [zen-disco-elected-as-master ([0] nodes joined)[, ]]])
 [2018-10-28T17:42:16,403][INFO ][o.e.x.s.t.n.SecurityNetty4HttpServerTransport] [Node1] publish_address {192.168.1.164:9200}, bound_addresses {192.168.1.164:9200}
 [2018-10-28T17:42:16,403][INFO ][o.e.n.Node ] [Node1] started
 [2018-10-28T17:42:16,600][INFO ][o.e.l.LicenseService ] [Node1] license [b2754b17-a4ec-47e4-9175-4b2e0d714a45] mode [basic] - valid

As you can see from my screen dump, the transport is bound to 192.168.1.164:9300. The REST HTTP interface is bound to 192.168.1.164:9200.