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Configure mongod and mongos for TLS/SSL

Overview

This document helps you to configure a new MongoDB instance to support TLS/SSL. For instructions on upgrading a cluster currently not using TLS/SSL to using TLS/SSL, see Upgrade a Cluster to Use TLS/SSL instead.

Starting in version 4.0, MongoDB uses the native TLS/SSL OS libraries:

Windows Secure Channel (Schannel)
Linux/BSD OpenSSL
macOS Secure Transport

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.
  • MongoDB’s TLS/SSL encryption only allows use of strong TLS/SSL ciphers with a minimum of 128-bit key length for all connections.
  • The Linux 64-bit legacy x64 builds of MongoDB do not include support for TLS/SSL.

Prerequisites

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.

Certificate Authorities

For production use, your MongoDB deployment should use valid certificates generated and signed by a single certificate authority. You or your organization can generate and maintain an independent certificate authority, or use certificates generated by a third-party TLS/SSL vendor. Obtaining and managing certificates is beyond the scope of this documentation.

Certificate Key File

When establishing a TLS/SSL connection, mongod/mongos presents a certificate key file (containing a public key certificate and its associated private key) to its clients to establish identity. [1]

MongoDB can use any valid TLS/SSL certificate issued by a certificate authority, or a self-signed certificate. If you use a self-signed certificate, although the communications channel will be encrypted, there will be no validation of server identity. Although such a situation will prevent eavesdropping on the connection, it leaves you vulnerable to a man-in-the-middle attack. Using a certificate signed by a trusted certificate authority will permit MongoDB drivers to verify the server’s identity.

In general, avoid using self-signed certificates unless the network is trusted.

Additionally, with regards to authentication among replica set/sharded cluster members, it is advisable to use different certificates on different servers. This minimizes exposure of the private key and allow hostname validation.

[1]For FIPS mode, ensure that the certificate is FIPS-compliant (i.e use of FIPS-compliant algorithms) and the private key meets the PKCS#8 standard. If you need to convert a private key to PKCS#8 format, various conversion tools exist, such as openssl pkcs8 and others.

Procedures

Set Up mongod and mongos with TLS/SSL Certificate and Key

The following section configures mongod/mongos to use TLS/SSL connections. With these TLS/SSL settings, mongod/mongos presents its certificate key file to the client. However, the mongod/mongos does not require a certificate key file from the client to verify the client’s identity. To require client’s certificate key file, see Set Up mongod and mongos with Client Certificate Validation instead.

To use TLS/SSL connections, include the following TLS/SSL settings in your mongod/mongos instance’s configuration file:

Setting Notes
net.ssl.mode

Set to requireSSL.

This setting restricts each server to use only TLS/SSL encrypted connections. You can also specify allowSSL or preferSSL to use mixed TLS/SSL modes. See net.ssl.mode for details.

net.ssl.PEMKeyFile

Set to the .pem file that contains the TLS/SSL certificate and key.

The mongod/mongos instance presents this file to its clients to establish the instance’s identity.

If the key is encrypted, specify the passphrase (net.ssl.PEMKeyPassword).

For example, consider the following configuration file for a mongod instance:

net:
   ssl:
      mode: requireSSL
      PEMKeyFile: /etc/ssl/mongodb.pem
systemLog:
   destination: file
   path: "/var/log/mongodb/mongod.log"
   logAppend: true
storage:
   dbPath: "/var/lib/mongodb"
processManagement:
   fork: true
net:
   bindIp: localhost,mongodb0.example.net
   port: 27017

Starting in MongoDB 4.0, you can use system SSL certificate stores for Windows and macOS. To use the system SSL certificate store, specify net.ssl.certificateSelector instead of specifying the certificate key file.

Setting Notes
net.ssl.mode

Set to requireSSL.

This setting restricts each server to use only TLS/SSL encrypted connections. You can also specify allowSSL or preferSSL to use mixed TLS/SSL modes. See net.ssl.mode for details.

net.ssl.certificateSelector

Set to the property (either subject or thumbprint) and value.

This setting is used to select the certificate. See net.ssl.certificateSelector for details.

For example, consider the following configuration file for a mongod instance:

net:
   ssl:
      mode: requireSSL
      certificateSelector: subject="<CertificateCommonName>"
systemLog:
   destination: file
   path: "/var/log/mongodb/mongod.log"
   logAppend: true
storage:
   dbPath: "/var/lib/mongodb"
processManagement:
   fork: true
net:
   bindIp: localhost,mongodb0.example.net
   port: 27017

A mongod instance that uses the above configuration can only use TLS/SSL connections:

mongod --config <path/to/configuration/file>

That is, clients must specify TLS/SSL connections. See Connect to MongoDB Instance Using Encryption for more information on connecting with TLS/SSL.

See also

You can also configure mongod and mongos using command-line options instead of the configuration file:

Set Up mongod and mongos with Client Certificate Validation

The following section configures mongod/mongos to use TLS/SSL connections and perform client certificate validation. With these TLS/SSL settings:

  • mongod/mongos presents its certificate key file to the client for verification.
  • mongod/mongos requires a certificate key file from the client to verify the client’s identity.

To use TLS/SSL connections and perform client certificate validation, include the following TLS/SSL settings in your mongod/mongos instance’s configuration file:

Note

Starting in MongoDB 4.0, you can use system SSL certificate stores for Windows and macOS. To use the system SSL certificate store, specify net.ssl.certificateSelector instead of specifying the certificate key file.

Setting Notes
net.ssl.mode

Set to requireSSL.

This setting restricts each server to use only TLS/SSL encrypted connections. You can also specify allowSSL or preferSSL to use mixed TLS/SSL modes. See net.ssl.mode for details.

net.ssl.PEMKeyFile

Set to the .pem file that contains the TLS/SSL certificate and key.

The mongod/mongos instance presents this file to its clients to establish the instance’s identity.

If the key is encrypted, specify the passphrase (net.ssl.PEMKeyPassword).

net.ssl.CAFile

Set to the path of the file that contains the certificate chain for verifying client certificates.

The mongod/mongos instance use this file to verify certificates presented by its clients. The certificate chain includes the certificate of the root Certificate Authority.

For example, consider the following configuration file for a mongod instance:

net:
   ssl:
      mode: requireSSL
      PEMKeyFile: /etc/ssl/mongodb.pem
      CAFile: /etc/ssl/caToValidateClientCertificates.pem
systemLog:
   destination: file
   path: "/var/log/mongodb/mongod.log"
   logAppend: true
storage:
   dbPath: "/var/lib/mongodb"
processManagement:
   fork: true
net:
   bindIp: localhost,mongodb0.example.net
   port: 27017

A mongod instance that uses the above configuration can only use TLS/SSL connections and requires valid certificate from its clients:

mongod --config <path/to/configuration/file>

That is, clients must specify TLS/SSL connections and presents its certificate key file to the instance. See Connect to MongoDB Instance that Requires Client Certificates for more information on connecting with TLS/SSL.

See also

You can also configure mongod and mongos using command-line options instead of the configuration file:

Block Revoked Certificates for Clients

To prevent clients with revoked certificates from connecting, include net.ssl.CRLFile set to a file that contains revoked certificates.

For example:

net:
  ssl:
    mode: requireSSL
    PEMKeyFile: /etc/ssl/mongodb.pem
    CAFile: /etc/ssl/caToValidateClientCertificates.pem
    CRLFile: /etc/ssl/revokedCertificates.pem

Clients who presents certificates that are listed in the /etc/ssl/revokedCertificates.pem will not be able to connect.

See also

You can also configure the revoked certificate list using the command-line option.

Validate Only if a Client Presents a Certificate

In most cases, it is important to ensure that clients present valid certificates. However, if you have clients that cannot present a client certificate or are transitioning to using a certificate, you may only want to validate certificates from clients that present a certificate.

To bypass client certificate validation for clients that do not present a certificate, include net.ssl.allowConnectionsWithoutCertificates set to true.

For example:

net:
  ssl:
    mode: requireSSL
    PEMKeyFile: /etc/ssl/mongodb.pem
    CAFile: /etc/ssl/caToValidateClientCertificates.pem
    allowConnectionsWithoutCertificates: true

A mongod/mongos running with these settings allows connection from:

  • Clients that do not present a certificate.
  • Clients that present a valid certificate.

Note

If the client presents a certificate, the certificate must be a valid certificate.

All connections, including those that have not presented certificates, are encrypted using TLS/SSL.

See TLS/SSL Configuration for Clients for more information on TLS/SSL connections for clients.

See also

You can also configure using the command-line options:

Disallow Protocols

New in version 3.0.7.

To prevent MongoDB servers from accepting incoming connections that use specific protocols, include net.ssl.disabledProtocols set to the disallowed protocols.

For example, the following configuration prevents mongod/mongos from accepting incoming connections that use either TLS1_0 or TLS1_1

net:
  ssl:
    mode: requireSSL
    PEMKeyFile: /etc/ssl/mongodb.pem
    CAFile: /etc/ssl/caToValidateClientCertificates.pem
    disabledProtocols: TLS1_0,TLS1_1

See also

You can also configure using the command-line options:

TLS/SSL Certificate Passphrase

The PEM files for PEMKeyfile and ClusterFile may be encrypted. With encrypted PEM files, you must specify the passphrase at startup with a command-line or a configuration file option or enter the passphrase when prompted.

To specify the passphrase in clear text on the command line or in a configuration file, use the PEMKeyPassword and/or the clusterPassword option.

To have MongoDB prompt for the passphrase at the start of mongod or mongos and avoid specifying the passphrase in clear text, omit the PEMKeyPassword and/or the clusterPassword option. MongoDB will prompt for each passphrase as necessary.

Important

The passphrase prompt option is available if you run the MongoDB instance in the foreground with a connected terminal. If you run mongod or mongos in a non-interactive session (e.g. without a terminal or as a service on Windows), you cannot use the passphrase prompt option.

Run in FIPS Mode

Note

FIPS-compatible TLS/SSL is available only in MongoDB Enterprise. See Configure MongoDB for FIPS for more information.

See Configure MongoDB for FIPS for more details.