Redis Enterprise Software (RS) uses self-signed certificates out-of-the-box to make sure that the product is secure by default. The self-signed certificates are used to establish encryption-in-transit for the following traffic:

  • Management Web UI (CM) - The certificate for connections to the management web UI
  • REST API - The certificate for REST API calls
  • Proxy - The certificate for connections between clients and database endpoints
  • Syncer - The certificate for synchronization between databases for ReplicaOf and CRDB
  • Metrics exporter - The certificate to export metrics to Prometheus

These self-signed certificates are generated on the first node of each RS installation and are copied to all other nodes added to the cluster.

When you use the default self-signed certificates, an untrusted connection notification is shown in the web UI. Depending on the browser you use, you can allow the connection for each session or add an exception to make the site trusted in future sessions.

Warning -
When you update the certificates, the new certificate replaces the same certificates on all nodes in the cluster.

How to update TLS certificates

You can use either the rladmin CLI or the REST API to update the certificates.

Using the CLI

To replace certificates using the rladmin CLI, run:

 rladmin cluster certificate set <cert-name> certificate_file <cert-file-name>.pem key_file <key-file-name>.pem

Where:

  • cert-name - The name of certificate you want to replace:
    • For management UI: cm
    • For REST API: api
    • For database endpoint: proxy
    • For syncer: syncer
    • For metrics exporter: metrics_exporter
  • cert-file-name - The name of your certificate file
  • key-file-name - The name of your key file

For example, to replace the cm certificate with the private key "key.pem" and the certificate file "cluster.pem":

rladmin cluster certificate set cm certificate_file cluster.pem key_file key.pem

Using the REST API

To replace a certificate using the REST API, run:

curl -k -X PUT -u "<username>:<password>" -H "Content-Type: application/json" -d '{ "name": "<cert_name>", "key": "<key>", "certificate": "<cert>" }' https://<cluster_address>:9443/v1/cluster/update_cert

Where:

  • cert_name - The name of the certificate to replace:
    • For management UI: cm
    • For REST API: api
    • For database endpoint: proxy
    • For syncer: syncer
    • For metrics exporter: metrics_exporter

  • key - The contents of the *_key.pem file

    Tip - 
    The key file contains `\n` end of line characters (EOL) that you cannot paste into the API call.
You can use `sed -z 's/\n/\\\n/g'` to escape the EOL characters.

  • cert - The contents of the *_cert.pem file

When you upgrade RS, the upgrade process copies the certificates on the first upgraded node to all of the nodes in the cluster.

TLS Protocol and Ciphers

TLS protocols and ciphers define the overall suite of algorithms that clients are able to connect to the servers with. You can change the TLS protocols and ciphers to improve the security posture of your RS cluster and databases. The default settings are in line with industry best practices, but you can customize them to match the security policy of your organization.

The communications for which you can modify TLS protocols and ciphers are:

  • Management path - The TLS configuration for cluster administration using the web UI and API.
  • Data path - The TLS configuration for the communication between the applications and the databases.
  • Discovery service (Sentinel) - The TLS configuration for the discovery service.

You can configure the TLS protocols and ciphers with the rladmin commands shown here, or with the REST API.

TLS protocol for the management path

To set the minimum TLS protocol for the management path:

  • Default TLS Protocols: TLSv1.0
  • Syntax: rladmin cluster config cluster config min_control_TLS_version <TLS_Version>
  • TLS versions available:
    • For TLSv1 - 1
    • For TLSv1.1 - 1.1
    • For TLSv1.2 - 1.2

For example:

rladmin cluster config min_control_TLS_version 1.2

TLS protocol for the data path and discovery service

To set the minimum TLS protocol for the data path:

  • Default TLS Protocols: TLSv1.0
  • Syntax: rladmin cluster config cluster config min_data_TLS_version <TLS_Version>
  • TLS versions available:
    • For TLSv1 - 1
    • For TLSv1.1 - 1.1
    • For TLSv1.2 - 1.2

For example:

rladmin cluster config min_data_TLS_version 1.2

For your changes to take effect on the discovery service, restart the service with the command:

supervisorctl restart sentinel_service

Enabling TLS for the discovery service

To enable TLS for the discovery service:

  • Default: Allows both TLS and non-TLS connections
  • Syntax: rladmin cluster config sentinel_ssl_policy <ssl_policy>
  • ssl_policy values available:
    • allowed - Allows both TLS and non-TLS connections
    • required - Allows only TLS connections
    • disabled - Allows only non-TLS connections

For example:

rladmin cluster config sentinel_ssl_policy required min_data_TLS_version 1.2

For your changes to take effect on the discovery service, restart the service with the command:

supervisorctl restart sentinel_service

After you set the minimum TLS version, RS does not accept communications with TLS versions older than the specified version.

Cipher Configuration

When you set the TLS ciphers, the new TLS ciphers are used for management communications only.

To set the TLS ciphers:

  • Default TLS Protocols: HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH
  • Syntax: rladmin cluster config cipher_suites '<openssl_cipher_list>'
  • The below example uses the Mozilla intermediate compatibility cipher list
rladmin cluster config cipher_suites 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384'