Singel Node Opens Too Many Connections

[chen-wu]

Hello.

We have an instance running in single node running on Windows. I saw that it opens a lot of connections to itself. Like:
TCP 127.0.0.1:9200 127.0.0.1:52540 ESTABLISHED 21936
TCP 127.0.0.1:9200 127.0.0.1:52669 ESTABLISHED 21936
TCP 127.0.0.1:52541 127.0.0.1:52542 ESTABLISHED 21936
It seems these ports (52540, 52669, 52541, 52542) are random.
However I have another application uses some port from 50000-60000. This application may stop working if the port is already used.
Is there any setting to disable this? Or can I modify the setting of this port range?
I tried http.port, transport.port. But they did not work.

[warkolm (Mark Walkom)]

Welcome!
What sort of things are connecting to Elasticsearch on that host?

[chen-wu]

Thanks Warkolm for your reply!
Nothing is connecting to the instance. I just start it.

[warkolm (Mark Walkom)]

What version are you on?

[chen-wu]

Sorry for lacking some information.
Version is 7.5.1. A standalone instance without Kibana or Logstash.
elasticsearch.yml:

cluster.name: testing
path.data: C:/ProgramData/es_data/data
path.logs: C:/ProgramData/es_data/logs
network.host: 0.0.0.0
http.port: 9200
transport.port: 9201-9300
discovery.type: single-node