Move own CA transport layer mtls guidance to security docs

deploy-manage/security/_snippets/own-ca-warning.md

@@ -0,0 +1,5 @@
+:::{warning}
+Transport connections between {{es}} nodes are security-critical and you must protect them carefully. Malicious actors who can observe or interfere with node-to-node transport traffic can read or modify cluster data. A malicious actor who can establish a transport connection might be able to invoke system-internal APIs, including APIs that read or modify cluster data.
+
+If you choose to issue node transport certificates using third-party tools, then carefully review [](/deploy-manage/security/self-tls-considerations.md) to ensure that the certificates that you provide meet the security requirements for transport connections.
+:::

deploy-manage/security/different-ca.md

@@ -15,6 +15,10 @@ products:
 
 If you have to trust a new CA from your organization, or you need to generate a new CA yourself, use this new CA to sign the new node certificates and instruct your nodes to trust the new CA.
 
+:::{include} ./_snippets/own-ca-warning.md
+:::
+
+
 ## Generate a new certificate for the transport layer [node-certs-different-transport]
 
 Create a new CA certificate, or get the CA certificate of your organization, and add it to your existing CA truststore. After you finish updating your certificates for all nodes, you can remove the old CA certificate from your truststore (but not before!).

deploy-manage/security/k8s-transport-settings.md

@@ -75,6 +75,9 @@ spec:
 
 ## Issue node transport certificates with third-party tools [k8s-transport-third-party-tools]
 
+:::{include} ./_snippets/own-ca-warning.md
+:::
+
 When following the instructions in [Configure a custom Certificate Authority](#k8s-transport-ca) the issuance of certificates is orchestrated by the ECK operator and the operator needs access to the CAs private key. If this is undesirable it is also possible to configure node transport certificates without involving the ECK operator. The following two pre-requisites apply:
 
 1. The tooling used must be able to issue individual certificates for each {{es}} node and dynamically add or remove certificates as the cluster scales up and down.

deploy-manage/security/same-ca.md

@@ -22,6 +22,9 @@ You don’t have to restart each node, but doing so forces new TLS connections a
 
 The following steps provide instructions for generating new node certificates and keys for both the transport layer and the HTTP layer. You might only need to replace one of these layer’s certificates depending on which of your certificates are expiring.
 
+:::{include} ./_snippets/own-ca-warning.md
+:::
+
 ::::{important}
 :name: cert-password-updates
 

deploy-manage/security/secure-cluster-communications.md

@@ -57,36 +57,43 @@ Securing this layer prevents unauthorized nodes from joining your cluster and pr
 
 The way that transport layer security is managed depends on your deployment type:
 
-::::{tab-set}
+:::::{tab-set}
 :group: deployments
 
-:::{tab-item} ECH and Serverless
+::::{tab-item} ECH and Serverless
 :sync: ech
 {{es}} transport security is fully managed by Elastic, and no configuration is required.
-:::
+::::
 
-:::{tab-item} ECE
+::::{admonition}{tab-item} ECE
 :sync: ece
 {{es}} transport security is fully managed by {{ece}} platform, and no configuration is required.
-:::
+::::
 
-:::{tab-item} ECK
+::::{tab-item} ECK
 :sync: eck
 
 :::{include} ./_snippets/eck-transport.md
 :::
 
+:::{include} ./_snippets/own-ca-warning.md
 :::
 
-:::{tab-item} Self-managed
+::::
+
+::::{tab-item} Self-managed
 :sync: self
 {{es}} transport security can be [automatically configured](self-auto-setup.md), or manually set up by following the steps in [](set-up-basic-security.md).
 
 For additional TLS configuration options, refer to [](./self-tls.md).
+
+:::{include} ./_snippets/own-ca-warning.md
 :::
 
 ::::
 
+:::::
+
 ### HTTP layer security [encrypt-http-communication]
 
 The HTTP layer includes the service endpoints exposed by both {{es}} and {{kib}}, supporting communications such as REST API requests, browser access to {{kib}}, and {{kib}}’s own traffic to {{es}}. Securing these endpoints helps prevent unauthorized access and protects sensitive data in transit.

deploy-manage/security/self-tls-considerations.md

@@ -0,0 +1,37 @@
+---
+navigation_title: Considerations
+applies_to:
+  deployment:
+    self:
+    eck:
+products:
+  - id: elasticsearch
+navigation_title: Private or 3P CA considerations
+---
+
+# Considerations for using an private or third-party CA for transport layer security
+
+By default, {{es}} uses mutual TLS (mTLS) to secure node-to-node transport connections. Mutual TLS means that data is encrypted in transit, ensuring confidentiality and integrity, and also that both nodes in a connection must present a valid certificate to the other node when establishing the connection. Each node requires that certificates be issued by a trusted certificate authority, ensuring that only authorized nodes can connect. Configure trusted certificate authorities using settings in the [`xpack.security.transport.ssl.*`](elasticsearch://reference/elasticsearch/configuration-reference/security-settings.md#transport-tls-ssl-settings) namespace, such as `xpack.security.transport.ssl.certificate_authorities` and `xpack.security.transport.ssl.truststore.path`. 
+
+::::{warning}
+Transport connections between {{es}} nodes are security-critical and you must protect them carefully. Malicious actors who can observe or interfere with unencrypted node-to-node transport traffic can read or modify cluster data. A malicious actor who can establish a transport connection might be able to invoke system-internal APIs, including APIs that read or modify cluster data.
+::::
+
+## mTLS transport certificate requirements for private or third-party CAs
+
+Obtain your transport certificates from a certificate authority that only issues certificates to {{es}} nodes permitted to connect to your cluster. Do not use a public certificate authority or an organization-wide private certificate authority, because these issue certificates to entities beyond your authorized cluster nodes. Use a dedicated private certificate authority for each {{es}} cluster.
+
+Certificates used for mTLS must either have no Extended Key Usage extension, or include both `clientAuth` and `serverAuth` values in the extension. Public certificate authorities typically omit the `clientAuth` value in the Extended Key Usage extension, making them unsuitable for mTLS. 
+
+### Transport certificates vs. HTTP certificates
+
+Transport certificates have different security requirements than [HTTP certificates](/deploy-manage/security/secure-cluster-communications.md#encrypt-http-communication). HTTP connections don't typically use mTLS because HTTP has its own authentication mechanisms. Because of this, HTTP certificates usually don't need to include the `clientAuth` value in their Extended Key Usage extension. HTTP certificates can come from public or organization-wide certificate authorities, while transport certificates should use a cluster-specific private CA. In most cases, you should not use the same certificate for both HTTP and transport connections.
+
+## Turning off mTLS for transport connections [turn-off-mtls]
+
+If your environment has some other way to prevent unauthorized node-to-node connections, you can disable mTLS by setting `xpack.security.transport.ssl.client_authentication: none`. You can still use non-mutual TLS to ensure the confidentiality and integrity of node-to-node traffic by setting `xpack.security.transport.ssl.enabled: true`. With non-mutual TLS, transport certificates don't require the `clientAuth` value in the Extended Key Usage extension.
+
+::::{warning}
+Turning off mTLS by setting `xpack.security.transport.ssl.client_authentication` to `optional` or `none` allows anyone with network access to establish transport connections. Malicious actors can use these connections to invoke system-internal APIs that may read or modify cluster data. Use mTLS to 
+protect your node-to-node transport connections unless you are absolutely certain that unauthorized network access to these nodes cannot occur.
+::::

deploy-manage/security/set-up-basic-security.md

@@ -17,26 +17,45 @@ Configuring TLS between nodes is the basic security setup to prevent unauthorize
 
 This document focuses on the **manual configuration** of TLS for [{{es}} transport protocol](./secure-cluster-communications.md#encrypt-internode-communication) in self-managed environments. Use this approach if you want to provide your own TLS certificates, generate them with Elastic’s tools, or have full control over the configuration. Alternatively, {{es}} can [automatically generate and configure HTTPS certificates](./self-auto-setup.md) for you.
 
-::::{note}
-For other deployment types, such as {{ech}}, {{ece}}, or {{eck}}, refer to [](./secure-cluster-communications.md).
-::::
-
 In this guide, you will learn how to:
 
-* [Generate a Certificate Authority (CA) and a server certificate using the `elasticsearch-certutil` tool](#generate-certificates).
+* [Either provide or generate security certificates](#obtain-certificates).
 * [Configure your {{es}} nodes to use the generated certificate for the transport layer](#encrypt-internode-communication).
 
 Refer to [Transport TLS/SSL settings](elasticsearch://reference/elasticsearch/configuration-reference/security-settings.md#transport-tls-ssl-settings) for the complete list of available settings in {{es}}.
 
-## Generate the certificate authority [generate-certificates]
+::::{note}
+For other deployment types, such as {{ech}}, {{ece}}, or {{eck}}, refer to [](./secure-cluster-communications.md).
+::::
+
+## Obtain certificates
 
 You can add as many nodes as you want in a cluster but they must be able to communicate with each other. The communication between nodes in a cluster is handled by the transport module. To secure your cluster, you must ensure that internode communications are encrypted and verified, which is achieved with mutual TLS.
 
 In a secured cluster, {{es}} nodes use certificates to identify themselves when communicating with other nodes.
 
 The cluster must validate the authenticity of these certificates. The recommended approach is to trust a specific certificate authority (CA). When nodes are added to your cluster they must use a certificate signed by the same CA.
 
-For the transport layer, we recommend using a separate, dedicated CA instead of an existing, possibly shared CA so that node membership is tightly controlled. Use the `elasticsearch-certutil` tool to generate a CA for your cluster.
+For the transport layer, we recommend using a separate, dedicated CA instead of an existing, possibly shared CA so that node membership is tightly controlled.
+
+When you manually set up transport TLS, you can choose from the following CA options: 
+
+* [Provide certificates from a private or third-party CA](#private-3p)
+* [Use the `elasticsearch-certutil` tool to generate a CA unique to your cluster](#generate-certificates)
+
+### Provide certificates from a private or third-party CA [private-3p]
+
+You might choose to use a private or third-party CA to generate transport certificates for node-to-node connections.
+
+Transport connections between {{es}} nodes are security-critical and you must protect them carefully. Malicious actors who can observe or interfere with unencrypted node-to-node transport traffic can read or modify cluster data. A malicious actor who can establish a transport connection might be able to invoke system-internal APIs, including APIs that read or modify cluster data.
+
+Carefully review [](/deploy-manage/security/self-tls-considerations.md) to ensure that the certificates that you provide meet the security requirements for transport connections.
+
+After you obtain your certificate, place the certificate file in the `$ES_PATH_CONF` directory on **every** node in your cluster. 
+
+### Generate the certificate authority using `elasticsearch-certutil`  [generate-certificates]
+
+You can use the `elasticsearch-certutil` tool to generate a CA for your cluster. Using `elasticsearch-certutil` guarantees that your certificates meet {{es}} certificate requirements and security best practices. 
 
 1. Before starting {{es}}, use the `elasticsearch-certutil` tool on any single node to generate a CA for your cluster.
 
@@ -59,7 +78,7 @@ For the transport layer, we recommend using a separate, dedicated CA instead of
         1. Enter the password for your CA, or press **Enter** if you did not configure one in the previous step.
         2. Create a password for the certificate and accept the default file name.
 
-            The output file is a keystore named `elastic-certificates.p12`. This file contains a node certificate, node key, and CA certificate.
+            The output file is a keystore named `elastSic-certificates.p12`. This file contains a node certificate, node key, and CA certificate.
 
 3. On **every** node in your cluster, copy the `elastic-certificates.p12` file to the `$ES_PATH_CONF` directory.
 
@@ -68,7 +87,9 @@ For the transport layer, we recommend using a separate, dedicated CA instead of
 
 The transport networking layer is used for internal communication between nodes in a cluster. When security features are enabled, you must use TLS to ensure that communication between the nodes is encrypted.
 
-Now that you’ve generated a certificate authority and certificates, you’ll update your cluster to use these files.
+Now that you’ve obtained your certificates, you’ll update your cluster to use these files.
+
+These steps assume that you [generated a CA and certificates](#generate-certificates) using `elasticsearch-certutil`. The `xpack.security.transport.ssl` settings that you need to set differ if you're using a private or third-party CA. Refer to [Transport TLS/SSL settings](elasticsearch://reference/elasticsearch/configuration-reference/security-settings.md#transport-tls-ssl-settings) full list of available settings.
 
 ::::{note}
 {{es}} monitors all files such as certificates, keys, keystores, or truststores that are configured as values of TLS-related node settings. If you update any of these files, such as when your hostnames change or your certificates are due to expire, {{es}} reloads them. The files are polled for changes at a frequency determined by the global {{es}} `resource.reload.interval.high` setting, which defaults to 5 seconds.

deploy-manage/toc.yml

@@ -488,6 +488,7 @@ toc:
                 children:
                   - file: security/k8s-https-settings.md
                   - file: security/k8s-transport-settings.md
+              - file: security/self-tls-considerations.md
           - file: security/network-security.md
             children:
               - file: security/network-security-policies.md