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Elastic Docs ›Elasticsearch Guide [7.10] ›Set up Elasticsearch ›Configuring Elasticsearch

Network settings

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Network settings

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Elasticsearch binds to localhost only by default. This is sufficient for you to run a local development server (or even a development cluster, if you start multiple nodes on the same machine), but you will need to configure some basic network settings in order to run a real production cluster across multiple servers.

Be careful with the network configuration!

Never expose an unprotected node to the public internet.

Commonly used network settings

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network.host

(Static) The node will bind to this hostname or IP address and publish (advertise) this host to other nodes in the cluster. Accepts an IP address, hostname, a special value, or an array of any combination of these. Note that any values containing a : (e.g., an IPv6 address or containing one of the special values) must be quoted because : is a special character in YAML. 0.0.0.0 is an acceptable IP address and will bind to all network interfaces. The value 0 has the same effect as the value 0.0.0.0.

Defaults to _local_.

discovery.seed_hosts

(Static) In order to join a cluster, a node needs to know the hostname or IP address of at least some of the other nodes in the cluster. This setting provides the initial list of addresses this node will try to contact. Accepts IP addresses or hostnames. If a hostname lookup resolves to multiple IP addresses then each IP address will be used for discovery. Round robin DNS — returning a different IP from a list on each lookup — can be used for discovery; non- existent IP addresses will throw exceptions and cause another DNS lookup on the next round of pinging (subject to JVM DNS caching).

Defaults to ["127.0.0.1", "[::1]"].

http.port

(Static) Port to bind to for incoming HTTP requests. Accepts a single value or a range. If a range is specified, the node will bind to the first available port in the range.

Defaults to 9200-9300.

transport.port

(Static) Port to bind for communication between nodes. Accepts a single value or a range. If a range is specified, the node will bind to the first available port in the range.

Defaults to 9300-9400.

Special values for network.host

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The following special values may be passed to network.host:

_local_
Any loopback addresses on the system, for example 127.0.0.1.
_site_
Any site-local addresses on the system, for example 192.168.0.1.
_global_
Any globally-scoped addresses on the system, for example 8.8.8.8.
_[networkInterface]_
Use the addresses of the network interface called [networkInterface]. For example if you wish to use the addresses of an interface called en0 then set network.host: _en0_.

IPv4 vs IPv6

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These special values will work over both IPv4 and IPv6 by default, but you can also limit this with the use of :ipv4 of :ipv6 specifiers. For example, _en0:ipv4_ would only bind to the IPv4 addresses of interface en0.

Discovery in the Cloud

More special settings are available when running in the Cloud with either the EC2 discovery plugin or the Google Compute Engine discovery plugin installed.

Advanced network settings

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The network.host setting explained in Commonly used network settings is a shortcut which sets the bind host and the publish host at the same time. In advanced used cases, such as when running behind a proxy server, you may need to set these settings to different values:

network.bind_host
This specifies which network interface(s) a node should bind to in order to listen for incoming requests. A node can bind to multiple interfaces, e.g. two network cards, or a site-local address and a local address. Defaults to network.host.
network.publish_host
The publish host is the single interface that the node advertises to other nodes in the cluster, so that those nodes can connect to it. Currently an Elasticsearch node may be bound to multiple addresses, but only publishes one. If not specified, this defaults to the “best” address from network.host, sorted by IPv4/IPv6 stack preference, then by reachability. If you set a network.host that results in multiple bind addresses yet rely on a specific address for node-to-node communication, you should explicitly set network.publish_host.

Both of the above settings can be configured just like network.host — they accept IP addresses, host names, and special values.

Advanced TCP settings

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Any component that uses TCP (like the HTTP and transport layers) share the following settings:

network.tcp.no_delay
(Static) Enable or disable the TCP no delay setting. Defaults to true.
network.tcp.keep_alive
(Static) Configures the SO_KEEPALIVE option for this socket, which determines whether it sends TCP keepalive probes.
network.tcp.keep_idle
(Static) Configures the TCP_KEEPIDLE option for this socket, which determines the time in seconds that a connection must be idle before starting to send TCP keepalive probes. Defaults to -1, which uses the system default. This value cannot exceed 300 seconds. Only applicable on Linux and macOS, and requires Java 11 or newer.
network.tcp.keep_interval
(Static) Configures the TCP_KEEPINTVL option for this socket, which determines the time in seconds between sending TCP keepalive probes. Defaults to -1, which uses the system default. This value cannot exceed 300 seconds. Only applicable on Linux and macOS, and requires Java 11 or newer.
network.tcp.keep_count
(Static) Configures the TCP_KEEPCNT option for this socket, which determines the number of unacknowledged TCP keepalive probes that may be sent on a connection before it is dropped. Defaults to -1, which uses the system default. Only applicable on Linux and macOS, and requires Java 11 or newer.
network.tcp.reuse_address
(Static) Should an address be reused or not. Defaults to true on non-windows machines.
network.tcp.send_buffer_size
(Static) The size of the TCP send buffer (specified with size units). By default not explicitly set.
network.tcp.receive_buffer_size
(Static) The size of the TCP receive buffer (specified with size units). By default not explicitly set.

HTTP and transport network communication

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Each Elasticsearch node uses the network for two different methods of communication:

The network settings described above apply to both methods of communication, and you can also configure each interface separately if needed. See the HTTP and transport pages for more details on their respective configurations.

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