This is an upcoming (i.e. in progress) version of the manual.

Appendix C - OpenSSL Client Certificates for Testing


This page is provided for testing purposes only and the certificates are for testing purposes only.

The following tutorial provides some basic steps for creating test x.509 certificates.

  • Do not use these certificates for production. Instead, follow your security policies.
  • For information on OpenSSL, refer to the official OpenSSL docs. Although this tutorial uses OpenSSL, the material should not be taken as an authoritative reference on OpenSSL.


The procedure outlined on this page uses the test intermediate authority certificate and key mongodb-test-ia.crt and mongodb-test-ia.key created in Appendix A - OpenSSL CA Certificate for Testing.


The following procedure outlines the steps to create test certificates for MongoDB clients. For steps to create test certificates for MongoDB servers, see Appendix B - OpenSSL Server Certificates for Testing.

A. Create the OpenSSL Configuration File

  1. Create a test configuration file openssl-test-client.cnf for your client with the following content:

    # NOT FOR PRODUCTION USE. OpenSSL configuration file for testing.
    [ req ]
    default_bits = 4096
    default_keyfile = myTestClientCertificateKey.pem    ## The default private key file name.
    default_md = sha256
    distinguished_name = req_dn
    req_extensions = v3_req
    [ v3_req ]
    subjectKeyIdentifier  = hash
    basicConstraints = CA:FALSE
    keyUsage = critical, digitalSignature, keyEncipherment
    nsComment = "OpenSSL Generated Certificate for TESTING only.  NOT FOR PRODUCTION USE."
    extendedKeyUsage  = serverAuth, clientAuth
    [ req_dn ]
    countryName = Country Name (2 letter code)
    countryName_default =
    countryName_min = 2
    countryName_max = 2
    stateOrProvinceName = State or Province Name (full name)
    stateOrProvinceName_default = TestClientCertificateState
    stateOrProvinceName_max = 64
    localityName = Locality Name (eg, city)
    localityName_default = TestClientCertificateLocality
    localityName_max = 64
    organizationName = Organization Name (eg, company)
    organizationName_default = TestClientCertificateOrg
    organizationName_max = 64
    organizationalUnitName = Organizational Unit Name (eg, section)
    organizationalUnitName_default = TestClientCertificateOrgUnit
    organizationalUnitName_max = 64
    commonName = Common Name (eg, YOUR name)
    commonName_max = 64
  2. Optional. You can update the default Distinguished Name (DN) values. Ensure that client certificates differ from server certificates with regards to at least one of the following attributes: Organization (O), the Organizational Unit (OU) or the Domain Component (DC).

B. Generate the Test PEM File for Client


Before proceeding, ensure that you have entered the appropriate DNS names in the [alt_names] section of the configuration file openssl-test-client.cnf.

  1. Create the test key file mongodb-test-client.key.

    openssl genrsa -out mongodb-test-client.key 4096
  2. Create the test certificate signing request mongodb-test-client.csr. When asked for Distinguished Name values, enter the appropriate values for your test certificate:


    The client certificate subject must differ to a server certificate subject with regards to at least one of the following attributes: Organization (O), the Organizational Unit (OU) or the Domain Component (DC).

    openssl req -new -key mongodb-test-client.key -out mongodb-test-client.csr -config openssl-test-client.cnf
  3. Create the test client certificate mongodb-test-client.crt.

    openssl x509 -sha256 -req -days 365 -in mongodb-test-client.csr -CA mongodb-test-ia.crt -CAkey mongodb-test-ia.key -CAcreateserial -out mongodb-test-client.crt -extfile openssl-test-client.cnf -extensions v3_req
  4. Create the test PEM file for the client.

    cat mongodb-test-client.crt mongodb-test-client.key > test-client.pem

    You can use the test PEM file to configure the mongo shell for TLS/SSL testing. For example, to connect to a mongod or a mongos:

    For MongoDB 4.2 or greater, include the following options for the client:

    mongo --tls --host <serverHost> --tlsCertificateKeyFile test-client.pem  --tlsCAFile test-ca.pem

    For MongoDB 4.0 and earlier, include the following options for the client:

    mongo --ssl --host <serverHost> --sslPEMKeyFile test-client.pem  --sslCAFile test-ca.pem
    On macOS,

    If you are testing with Keychain Access to manage certificates, create a PKCS 12 file to add to Keychain Access instead of a PEM file:

    openssl pkcs12 -export -out test-client.pfx -inkey mongodb-test-client.key -in mongodb-test-client.crt -certfile mongodb-test-ia.crt

    Once added to Keychain Access, instead of specifying the Certificate Key file, you can use the --tlsCertificateSelector to specify the certificate to use. If the CA file is also in Keychain Access, you can omit --tlsCAFile as well as in the following example:

    For MongoDB 4.2 or greater

    mongo --tls --tlsCertificateSelector subject="<TestClientCertificateCommonName>"

    Although still available, --ssl and --sslCertificateSelector are deprecated as of MongoDB 4.2.

    For MongoDB 4.0 and earlier

    mongo --ssl --sslCertificateSelector subject="<TestClientCertificateCommonName>"

    For adding certificates to Keychain Access, refer to your official documentation for Keychain Access.