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Upgrade a Cluster to Use TLS/SSL

Note

Starting in version 4.0, MongoDB disables support for TLS 1.0 encryption on systems where TLS 1.1+ is available. For more details, see Disable TLS 1.0.

Important

A full description of TLS/SSL, PKI (Public Key Infrastructure) certificates, and Certificate Authority is beyond the scope of this document. This page assumes prior knowledge of TLS/SSL as well as access to valid certificates.

The MongoDB server supports listening for both TLS/SSL encrypted and unencrypted connections on the same TCP port. This allows upgrades of MongoDB clusters to use TLS/SSL encrypted connections.

To upgrade from a MongoDB cluster using no TLS/SSL encryption to one using only TLS/SSL encryption, use the following rolling upgrade process:

  1. For each node of a cluster, start the node with the command-line option --sslMode or the configuration file option net.ssl.mode set to allowSSL. The allowSSL setting allows the node to accept both TLS/SSL and non-TLS/non-SSL incoming connections. Its connections to other servers do not use TLS/SSL. Include other TLS/SSL options [2] as well as any other options that are required for your specific configuration.

    Note

    Starting in MongoDB 3.6, mongod and mongos bind to localhost by default. If the members of your deployment are run on different hosts or if you wish remote clients to connect to your deployment, you must specify --bind_ip or net.bindIp. For more information, see Localhost Binding Compatibility Changes.

    For example:

    mongod --replSet <name> --sslMode allowSSL --sslPEMKeyFile <path to TLS/SSL Certificate and key PEM file> --sslCAFile <path to root CA PEM file> <additional options>
    

    To specify these options in the configuration file, include the following settings in the file:

    net:
       ssl:
          mode: <allowSSL>
          PEMKeyFile: <path to TLS/SSL certificate and key PEM file>
          CAFile: <path to root CA PEM file>
    

    Upgrade all nodes of the cluster to these settings.

  2. Switch all clients to use TLS/SSL. See TLS/SSL Configuration for Clients.

  3. For each node of a cluster, use the setParameter command to update the sslMode to preferSSL. [1] With preferSSL as its net.ssl.mode, the node accepts both TLS/SSL and non-TLS/non-SSL incoming connections, and its connections to other servers use TLS/SSL. For example:

    db.adminCommand( { setParameter: 1, sslMode: "preferSSL" } )
    

    Upgrade all nodes of the cluster to these settings.

    At this point, all connections should be using TLS/SSL.

  4. For each node of the cluster, use the setParameter command to update the sslMode to requireSSL. [1] With requireSSL as its net.ssl.mode, the node will reject any non-TLS/non-SSL connections. For example:

    db.adminCommand( { setParameter: 1, sslMode: "requireSSL" } )
    
  5. After the upgrade of all nodes, edit the configuration file with the appropriate TLS/SSL settings to ensure that upon subsequent restarts, the cluster uses TLS/SSL.

[1](1, 2) As an alternative to using the setParameter command, you can also restart the nodes with the appropriate TLS/SSL options and values.
[2]

Starting in MongoDB 4.0, you can use system SSL certificate stores for Windows and macOS. To use the system SSL certificate store, use --sslCertificateSelector (or the net.ssl.certificateSelector configuration file setting) instead of --sslPEMKeyFile (or the net.ssl.mode configuration file setting).

When using the system SSL certificate store, OCSP (Online Certificate Status Protocol) is used to validate the revocation status of certificates.