259 lines
12 KiB
Plaintext
259 lines
12 KiB
Plaintext
[[ssl-tls]]
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=== Setting Up SSL/TLS on a Cluster
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{security} enables you to encrypt traffic to, from and within your Elasticsearch
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cluster. Connections are secured using Transport Layer Security (TLS), which is
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commonly referred to as "SSL".
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WARNING: Clusters that do not have encryption enabled send all data in plain text
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including passwords.
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To enable encryption, you need to perform the following steps on each node in
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the cluster:
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. <<installing-node-certificates, Generate a private key and X.509 certificate>>.
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. <<configure-ssl, Configure the node>> to:
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.. Identify itself using its signed certificate.
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.. Enable SSL on the transport and HTTP layers.
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. Restart Elasticsearch.
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[[installing-node-certificates]]
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==== Node Certificates
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TLS requires X.509 certificates to perform encryption and authentication of the application
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that is being communicated with. In order for the communication between nodes to be truly
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secure, the certificates must be validated. The recommended approach for validating
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certificate authenticity in a Elasticsearch cluster is to trust the certificate authority (CA)
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that signed the certificate. By doing this, as nodes are added to your cluster they just need
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to use a certificate signed by the same CA and the node is automatically allowed to join the
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cluster. Additionally, it is recommended that the certificates contain subject alternative
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names (SAN) that correspond to the node's ip address and dns name so that hostname verification
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can be performed.
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In order to simplify the process of generating certificates for the Elastic Stack, a command
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line tool, `certgen` has been included with {xpack}. This tool takes care of the generating
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a CA and signing certificates with the CA. `certgen` can be used interactively or in a silent
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mode through the use of an input file. The `certgen` tool also supports generation of certificate
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signing requests (CSR), so that a commercial or organization specific CA may be used to sign
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the certificates.
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NOTE: If you choose not to use the `certgen`, the certificates that you obtain must allow for both
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`clientAuth` and `serverAuth` if the extended key usage extension is present. The certificates
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need to be in PEM format. Although not required, it is highly recommended that the certificate contain
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the dns name(s) and/or ip address(es) of the node so that hostname verification may be used.
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[[generating-signed-certificates]]
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===== Generating Certificates with `certgen`
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The `certgen` tool can be used to generate a CA and signed certificates for your nodes. The tool
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can be used interactively:
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[listing]
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....
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bin/x-pack/certgen
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This tool assists you in the generation of X.509 certificates and certificate
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signing requests for use with SSL in the Elastic stack. Depending on the command
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line option specified, you may be prompted for the following:
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* The path to the output file
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* The output file is a zip file containing the signed certificates and
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private keys for each instance. If a Certificate Authority was generated,
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the certificate and private key will also be included in the output file.
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* Information about each instance
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* An instance is any piece of the Elastic Stack that requires a SSL certificate.
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Depending on your configuration, Elasticsearch, Logstash, Kibana, and Beats
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may all require a certificate and private key.
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* The minimum required value for each instance is a name. This can simply be the
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hostname, which will be used as the Common Name of the certificate. A full
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distinguished name may also be used.
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* IP addresses and DNS names are optional. Multiple values can be specified as a
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comma separated string. If no IP addresses or DNS names are provided, you may
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disable hostname verification in your SSL configuration.
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* Certificate Authority private key password
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* The password may be left empty if desired.
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Let's get started...
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Please enter the desired output file [/home/es/config/x-pack/certificate-bundle.zip]:
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Enter instance name: node01
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Enter name for directories and files [node01]:
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Enter IP Addresses for instance (comma-separated if more than one) []: 10.10.0.1
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Enter DNS names for instance (comma-separated if more than one) []: node01.mydomain.com,node01
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Would you like to specify another instance? Press 'y' to continue entering instance information: y
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Enter instance name: node02
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Enter name for directories and files [node02]:
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Enter IP Addresses for instance (comma-separated if more than one) []: 10.10.0.2
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Enter DNS names for instance (comma-separated if more than one) []: node02.mydomain.com
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Would you like to specify another instance? Press 'y' to continue entering instance information:
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Certificates written to /home/es/config/x-pack/certificate-bundle.zip
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This file should be properly secured as it contains the private keys for all
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instances and the certificate authority.
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After unzipping the file, there will be a directory for each instance containing
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the certificate and private key. Copy the certificate, key, and CA certificate
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to the configuration directory of the Elastic product that they will be used for
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and follow the SSL configuration instructions in the product guide.
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For client applications, you may only need to copy the CA certificate and
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configure the client to trust this certificate.
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....
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The usage of `certgen` above generates a zip file with the CA certificate, private key, two signed certificates and keys
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in PEM format for `node01` and `node02`.
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[[generating-csr]]
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===== Generating Certificate Signing Requests with `certgen`
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When using a commercial or organization specific CA, the `certgen` tool may be used to generate
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certificate signing requests (CSR) for the nodes in your cluster:
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[listing]
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....
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bin/x-pack/certgen -csr
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This tool assists you in the generation of X.509 certificates and certificate
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signing requests for use with SSL in the Elastic stack. Depending on the command
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line option specified, you may be prompted for the following:
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* The path to the output file
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* The output file is a zip file containing the certificate signing requests
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and private keys for each instance.
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* Information about each instance
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* An instance is any piece of the Elastic Stack that requires a SSL certificate.
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Depending on your configuration, Elasticsearch, Logstash, Kibana, and Beats
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may all require a certificate and private key.
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* The minimum required value for each instance is a name. This can simply be the
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hostname, which will be used as the Common Name of the certificate. A full
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distinguished name may also be used.
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* IP addresses and DNS names are optional. Multiple values can be specified as a
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comma separated string. If no IP addresses or DNS names are provided, you may
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disable hostname verification in your SSL configuration.
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Let's get started...
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Please enter the desired output file [/home/es/config/x-pack/csr-bundle.zip]:
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Enter instance name: node01
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Enter name for directories and files [node01]:
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Enter IP Addresses for instance (comma-separated if more than one) []: 10.10.0.1
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Enter DNS names for instance (comma-separated if more than one) []: node01.mydomain.com,node01
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Would you like to specify another instance? Press 'y' to continue entering instance information: y
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Enter instance name: node02
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Enter name for directories and files [node02]:
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Enter IP Addresses for instance (comma-separated if more than one) []: 10.10.0.2
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Enter DNS names for instance (comma-separated if more than one) []: node02.mydomain.com
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Would you like to specify another instance? Press 'y' to continue entering instance information:
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Certificate signing requests written to /Users/jmodi/dev/tmp/elasticsearch-5.0.0-alpha5-SNAPSHOT/config/x-pack/csr-bundle.zip
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This file should be properly secured as it contains the private keys for all
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instances.
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After unzipping the file, there will be a directory for each instance containing
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the certificate signing request and the private key. Provide the certificate
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signing requests to your certificate authority. Once you have received the
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signed certificate, copy the signed certificate, key, and CA certificate to the
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configuration directory of the Elastic product that they will be used for and
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follow the SSL configuration instructions in the product guide.
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....
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The usage of `certgen` above generates a zip file with two CSRs and private
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keys. The CSRs should be provided to the CA in order to obtain the signed
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certificates. The signed certificates will need to be in PEM format in order to
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be used.
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===== Using `certgen` in Silent Mode
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`certgen` supports a silent mode of operation to enable easier batch operations. In order
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to use this mode, a YAML file containing the information about the instances needs to be
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created matching the format shown below:
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[source, yaml]
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--------------------------------------------------
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instances:
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- name: "node1" <1>
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ip: <2>
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- "192.0.2.1"
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dns: <3>
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- "node1.mydomain.com"
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- name: "node2"
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ip:
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- "192.0.2.2"
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- "198.51.100.1"
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- name: "node3"
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- name: "node4"
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dns:
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- "node4.mydomain.com"
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- "node4.internal"
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- name: "CN=node5,OU=IT,DC=mydomain,DC=com"
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filename: "node5" <4>
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--------------------------------------------------
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<1> The name of the instance. This can be a simple string value or can be a Distinguished Name (DN). This is the only required field.
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<2> An optional array of strings that represent IP Addresses for this instance. Both IPv4 and IPv6 values are allowed. The values will
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be added as Subject Alternative Names.
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<3> An optional array of strings that represent DNS names for this instance. The values will be added as Subject Alternative Names.
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<4> The filename to use for this instance. This name will be the name of the directory in the zip file that this instance's files will
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stored in and it will used be used in the naming of the files within the directory. This filename should not have an extension. Note: If
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the `name` provided for the instance does not represent a valid filename, then the `filename` field must be present.
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With the YAML file ready, the `certgen` tool can be used to generate certificates or certificate signing requests. Simply pass the file's
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path to `certgen` using the `-in` option. For example:
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[source, sh]
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--------------------------------------------------
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bin/x-pack/certgen -in instances.yml <1>
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--------------------------------------------------
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<1> Generates a CA certificate and private key in addition to certificates and private keys for the instances
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contained in the YAML file. The other options to the tool can be specified in addition to the `-in` option. For all of the available
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options, run `bin/x-pack/certgen -h`.
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[[enable-ssl]]
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==== Enabling SSL in the Node Configuration
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Once you have the signed certificate, private key, and CA certificate you need to
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modify the node configuration to enable SSL.
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[[configure-ssl]]
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To enable SSL, make the following changes in `elasticsearch.yml`:
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. Specify the location of the node's keystore and the password(s) needed to
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access the node's certificate. For example:
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+
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--
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[source, yaml]
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--------------------------------------------------
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xpack.ssl.key: /home/es/config/x-pack/node01.key <1>
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xpack.ssl.certificate: /home/es/config/x-pack/node01.crt <2>
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xpack.ssl.certificate_authorities: [ "/home/es/config/x-pack/ca.crt" ] <3>
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--------------------------------------------------
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<1> The full path to the node key file. This must be a location within the
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Elasticsearch configuration directory.
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<2> The full path to the node certificate. This must be a location within the
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Elasticsearch configuration directory.
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<3> An array of paths to the CA certificates that should be trusted. These paths
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must be a location within the Elasticsearch configuration directory.
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--
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. Enable SSL on the transport networking layer to ensure that communication
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between nodes is encrypted:
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+
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[source, yaml]
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--------------------------------------------------
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xpack.security.transport.ssl.enabled: true
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--------------------------------------------------
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+
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. Enable SSL on the HTTP layer to ensure that communication between HTTP clients
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and the cluster is encrypted:
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+
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[source, yaml]
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--------------------------------------------------
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xpack.security.http.ssl.enabled: true
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--------------------------------------------------
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+
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. Restart Elasticsearch.
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NOTE: All SSL related node settings that are considered to be highly sensitive
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and therefore are not exposed via the
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{ref}/cluster-nodes-info.html#cluster-nodes-info[nodes info API].
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