[[separating-node-client-traffic]]
=== Separating node to node and client traffic

Elasticsearch has the feature of so called {ref}/modules-transport.html#_tcp_transport_profiles[tcp transport profiles].
This allows Elasticsearch to bind to several ports and addresses. Shield extends on this functionality to enhance the
security of the cluster by enabling the separation of node to node transport traffic from client transport traffic. This
is important if the client transport traffic is not trusted and could potentially be malicious. To separate the node to
node traffic from the client traffic, add the following to `elasticsearch.yml`:

[source, yaml]
--------------------------------------------------
transport.profiles.client<1>:
  port: 9500-9600 <2>
  shield:
    type: client <3>
--------------------------------------------------
<1> `client` is the name of this example profile
<2> The port range that will be used by transport clients to communicate with this cluster
<3> A type of `client` enables additional filters for added security by denying internal cluster operations (e.g shard
level actions and ping requests)

If supported by your environment, an internal network can be used for node to node traffic and public network can be
used for client traffic by adding the following to `elasticsearch.yml`:
[source, yaml]
--------------------------------------------------
transport.profiles.default.bind_host: 10.0.0.1 <1>
transport.profiles.client.bind_host: 1.1.1.1 <2>
--------------------------------------------------
<1> The bind address for the network that will be used for node to node communication
<2> The bind address for the network used for client communication

If separate networks are not available, then <<ip-filtering, IP Filtering>> can be enabled to limit access to the profiles.

The tcp transport profiles also allow for enabling SSL on a per profile basis. This is useful if you have a secured network
for the node to node communication, but the client is on an unsecured network. To enable SSL on a client profile when SSL is
disabled for node to node communication, add the following to `elasticsearch.yml`:
[source, yaml]
--------------------------------------------------
transport.profiles.client.ssl: true <1>
--------------------------------------------------
<1> This enables SSL on the client profile. The default value for this setting is the value of `shield.transport.ssl`.

When using SSL for transport, a different set of certificates can also be used for the client traffic by adding the
following to `elasticsearch.yml`:
[source, yaml]
--------------------------------------------------
transport.profiles.client.shield.truststore:
  path: /path/to/another/truststore
  password: changeme

transport.profiles.client.shield.keystore:
  path: /path/to/another/keystore
  password: changeme
--------------------------------------------------

To change the default behavior that requires certificates for transport clients, set the following value in the `elasticsearch.yml` 
file:

[source, yaml]
--------------------------------------------------
transport.profiles.client.shield.ssl.client.auth: no
--------------------------------------------------

This setting keeps certificate authentication active for node-to-node traffic, but removes the requirement to distribute
a signed certificate to transport clients. Please see the <<transport-client, Transport Client>> section.
