# Will es nodes connect with each other in 9200?

**URL:** <https://discuss.elastic.co/t/will-es-nodes-connect-with-each-other-in-9200/300421>\
**Category:** Elasticsearch\
**Created:** [March 23, 2022, 8:30am UTC](https://discuss.elastic.co/t/will-es-nodes-connect-with-each-other-in-9200/300421 "2022-03-23T08:30:48Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![JohnPhilip](https://avatars.discourse-cdn.com/v4/letter/j/57b2e6/32.png) [@JohnPhilip](https://discuss.elastic.co/u/JohnPhilip)\
**Post date:** [March 23, 2022, 8:30am UTC](https://discuss.elastic.co/t/will-es-nodes-connect-with-each-other-in-9200/300421/1 "2022-03-23T08:30:48Z")

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Hi, there.  
The official [doc](https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-network.html#modules-network) said,

> Each Elasticsearch node has two different network interfaces. Clients send requests to Elasticsearch’s REST APIs using its [HTTP interface](https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-network.html#http-settings), but nodes communicate with other nodes using the [transport interface](https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-network.html#transport-settings). The transport interface is also used for communication with [remote clusters](https://www.elastic.co/guide/en/elasticsearch/reference/current/remote-clusters.html).

So can I understand there will be no traffic of 9200 if there is no external client to access the rest interface?

I was curious about this because I found that when I use

```auto
lsof -i:9200

```

and there are many established connections.

```auto
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
java 18801 elasticsearch 360u IPv4 4246429501 0t0 TCP strees:wap->10.10.6.15:35059 (ESTABLISHED)
java 18801 elasticsearch 561u IPv4 4179746514 0t0 TCP *:wap (LISTEN)
java 18801 elasticsearch 578u IPv4 63089845 0t0 TCP strees:wap->10.10.20.116:51088 (ESTABLISHED)
java 18801 elasticsearch 612u IPv4 4184040085 0t0 TCP strees:wap->10.10.20.31:64112 (ESTABLISHED)

```

what are they used for?

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<div class="post-metadata">

**Author:** ![JohnPhilip](https://avatars.discourse-cdn.com/v4/letter/j/57b2e6/32.png) [@JohnPhilip](https://discuss.elastic.co/u/JohnPhilip)\
**Post date:** [March 23, 2022, 9:53am UTC](https://discuss.elastic.co/t/will-es-nodes-connect-with-each-other-in-9200/300421/2 "2022-03-23T09:53:26Z")

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After use tcpdump I found it's monitoring data(I also deploy a kibana in my environment), and I found that there already described that [What are ports 9200 and 9300 used for?](https://discuss.elastic.co/t/what-are-ports-9200-and-9300-used-for/238578)

> - **Port 9200** is used for all API calls over HTTP. This includes search and aggregations, monitoring and anything else that uses a HTTP request. All client libraries will use this port to talk to Elasticsearch

So it is the monitoring request cause this.  
Sorry for disturbance.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [April 20, 2022, 9:53am UTC](https://discuss.elastic.co/t/will-es-nodes-connect-with-each-other-in-9200/300421/3 "2022-04-20T09:53:54Z")

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