Provided by: libmongoc-doc_1.16.1-1build2_all 
NAME
mongoc_authentication - Authentication
This guide covers the use of authentication options with the MongoDB C Driver. Ensure that the MongoDB
server is also properly configured for authentication before making a connection. For more information,
see the MongoDB security documentation.
The MongoDB C driver supports several authentication mechanisms through the use of MongoDB connection
URIs.
By default, if a username and password are provided as part of the connection string (and an optional
authentication database), they are used to connect via the default authentication mechanism of the
server.
To select a specific authentication mechanism other than the default, see the list of supported mechanism
below.
mongoc_client_t *client = mongoc_client_new ("mongodb://user:password@localhost/?authSource=mydb");
Currently supported values for the authMechanism connection string option are:
• SCRAM-SHA-1
• MONGODB-CR (deprecated)
• GSSAPI
• PLAIN
• X509
BASIC AUTHENTICATION (SCRAM-SHA-256)
MongoDB 4.0 introduces support for authenticating using the SCRAM protocol with the more secure SHA-256
hash described in RFC 7677. Using this authentication mechanism means that the password is never actually
sent over the wire when authenticating, but rather a computed proof that the client password is the same
as the password the server knows. In MongoDB 4.0, the C driver can determine the correct default
authentication mechanism for users with stored SCRAM-SHA-1 and SCRAM-SHA-256 credentials:
mongoc_client_t *client = mongoc_client_new ("mongodb://user:password@localhost/?authSource=mydb");
/* the correct authMechanism is negotiated between the driver and server. */
Alternatively, SCRAM-SHA-256 can be explicitly specified as an authMechanism.
mongoc_client_t *client = mongoc_client_new ("mongodb://user:password@localhost/?authMechanism=SCRAM-SHA-256&authSource=mydb");
Passwords for SCRAM-SHA-256 undergo the preprocessing step known as SASLPrep specified in RFC 4013.
SASLPrep will only be performed for passwords containing non-ASCII characters. SASLPrep requires libicu.
If libicu is not available, attempting to authenticate over SCRAM-SHA-256 with non-ASCII passwords will
result in error.
Usernames never undergo SASLPrep.
By default, when building the C driver libicu is linked if available. This can be changed with the
ENABLE_ICU cmake option. To specify an installation path of libicu, specify ICU_ROOT as a cmake option.
See the FindICU documentation for more information.
BASIC AUTHENTICATION (SCRAM-SHA-1)
The default authentication mechanism before MongoDB 4.0 is SCRAM-SHA-1 (RFC 5802). Using this
authentication mechanism means that the password is never actually sent over the wire when
authenticating, but rather a computed proof that the client password is the same as the password the
server knows.
mongoc_client_t *client = mongoc_client_new ("mongodb://user:password@localhost/?authMechanism=SCRAM-SHA-1&authSource=mydb");
NOTE:
SCRAM-SHA-1 authenticates against the admin database by default. If the user is created in another
database, then specifying the authSource is required.
LEGACY AUTHENTICATION (MONGODB-CR)
The MONGODB-CR authMechanism is deprecated and will no longer function in MongoDB 4.0. Instead, specify
no authMechanism and the driver will use an authentication mechanism compatible with your server.
GSSAPI (KERBEROS) AUTHENTICATION
NOTE:
Kerberos support requires compiling the driver against cyrus-sasl on UNIX-like environments. On
Windows, configure the driver to build against the Windows Native SSPI.
GSSAPI (Kerberos) authentication is available in the Enterprise Edition of MongoDB. To authenticate using
GSSAPI, the MongoDB C driver must be installed with SASL support.
On UNIX-like environments, run the kinit command before using the following authentication methods:
$ kinit mongodbuser@EXAMPLE.COM
mongodbuser@EXAMPLE.COM's Password:
$ klistCredentials cache: FILE:/tmp/krb5cc_1000
Principal: mongodbuser@EXAMPLE.COM
Issued Expires Principal
Feb 9 13:48:51 2013 Feb 9 23:48:51 2013 krbtgt/EXAMPLE.COM@EXAMPLE.COM
Now authenticate using the MongoDB URI. GSSAPI authenticates against the $external virtual database, so a
database does not need to be specified in the URI. Note that the Kerberos principal must be URL-encoded:
mongoc_client_t *client;
client = mongoc_client_new ("mongodb://mongodbuser%40EXAMPLE.COM@mongo-server.example.com/?authMechanism=GSSAPI");
NOTE:
GSSAPI authenticates against the $external database, so specifying the authSource database is not
required.
The driver supports these GSSAPI properties:
• CANONICALIZE_HOST_NAME: This might be required with Cyrus-SASL when the hosts report different
hostnames than what is used in the Kerberos database. The default is "false".
• SERVICE_NAME: Use a different service name than the default, "mongodb".
Set properties in the URL:
mongoc_client_t *client;
client = mongoc_client_new ("mongodb://mongodbuser%40EXAMPLE.COM@mongo-server.example.com/?authMechanism=GSSAPI&"
"authMechanismProperties=SERVICE_NAME:other,CANONICALIZE_HOST_NAME:true");
If you encounter errors such as Invalid net address, check if the application is behind a NAT (Network
Address Translation) firewall. If so, create a ticket that uses forwardable and addressless Kerberos
tickets. This can be done by passing -f -A to kinit.
$ kinit -f -A mongodbuser@EXAMPLE.COM
SASL PLAIN AUTHENTICATION
NOTE:
The MongoDB C Driver must be compiled with SASL support in order to use SASL PLAIN authentication.
MongoDB Enterprise Edition supports the SASL PLAIN authentication mechanism, initially intended for
delegating authentication to an LDAP server. Using the SASL PLAIN mechanism is very similar to the
challenge response mechanism with usernames and passwords. This authentication mechanism uses the
$external virtual database for LDAP support:
NOTE:
SASL PLAIN is a clear-text authentication mechanism. It is strongly recommended to connect to MongoDB
using SSL with certificate validation when using the PLAIN mechanism.
mongoc_client_t *client;
client = mongoc_client_new ("mongodb://user:password@example.com/?authMechanism=PLAIN");
PLAIN authenticates against the $external database, so specifying the authSource database is not
required.
X.509 CERTIFICATE AUTHENTICATION
NOTE:
The MongoDB C Driver must be compiled with SSL support for X.509 authentication support. Once this is
done, start a server with the following options:
$ mongod --sslMode requireSSL --sslPEMKeyFile server.pem --sslCAFile ca.pem
The MONGODB-X509 mechanism authenticates a username derived from the distinguished subject name of the
X.509 certificate presented by the driver during SSL negotiation. This authentication method requires the
use of SSL connections with certificate validation.
mongoc_client_t *client;
mongoc_ssl_opt_t ssl_opts = { 0 };
ssl_opts.pem_file = "mycert.pem";
ssl_opts.pem_pwd = "mycertpassword";
ssl_opts.ca_file = "myca.pem";
ssl_opts.ca_dir = "trust_dir";
ssl_opts.weak_cert_validation = false;
client = mongoc_client_new ("mongodb://x509_derived_username@localhost/?authMechanism=MONGODB-X509");
mongoc_client_set_ssl_opts (client, &ssl_opts);
MONGODB-X509 authenticates against the $external database, so specifying the authSource database is not
required. For more information on the x509_derived_username, see the MongoDB server x.509 tutorial.
NOTE:
The MongoDB C Driver will attempt to determine the x509 derived username when none is provided, and as
of MongoDB 3.4 providing the username is not required at all.
AUTHOR
MongoDB, Inc
COPYRIGHT
2017-present, MongoDB, Inc
1.16.1 Mar 03, 2020 MONGOC_AUTHENTICATION(3)