When using cross-cluster search you need to take extra steps to secure communications with the connected clusters.
You will need to update the configuration for several clients to work with a secured cluster:
The Elasticsearch security features enable you to secure your Elasticsearch cluster. But Elasticsearch itself is only one product within the Elastic Stack. It is often the case that other products in the stack are connected to the cluster and therefore need to be secured as well, or at least communicate with the cluster in a secured way: