Defining a Kerberos Scheme

Prerequisites

Completely set up Kerberos for DSE nodes before turning on Kerberos authentication. When switching authentication methods, or enabling authentication for the first time in a production environment, DataStax recommends setting up applications to use Kerberos tickets before restricting access to only authenticated connections. When DSE Authenticator is disabled, the credentials portion of the connection request is ignored. Therefore, you can pass Kerberos tickets to DSE before implementing authentication in the environment.

Change the replication strategy and default replication factor for the system_auth and dse_security keyspaces, see Configuring system_auth keyspace replication

The following procedure describes how to add the Kerberos authenticator to cassandra.yaml and Kerberos options to dse.yaml.

Procedure

Locate the cassandra.yaml configuration file. The location of this file depends on the type of installation:
- Package installations: /etc/dse/cassandra/cassandra.yaml
- Tarball installations: <installation_location>/resources/cassandra/conf/cassandra.yaml
On each node, edit the cassandra.yaml file to set the authenticator to the DSE Authenticator.
```
authenticator: com.datastax.bdp.cassandra.auth.DseAuthenticator
```
Set the native_transport_address and listen_address to the IP address. Do not use localhost or the hostname.
```
native_transport_address: 100.200.182.1
listen_address: 100.200.182.1
```
Locate the dse.yaml configuration file. The location of this file depends on the type of installation:
- Package installations: /etc/dse/dse.yaml
- Tarball installations: <installation_location>/resources/dse/conf/dse.yaml

On each node, edit the dse.yaml file:

Set Kerberos as default or other scheme in the authentication options:

authentication_options:
    enabled: false
    default_scheme: kerberos
    other_schemes:
        - internal
    scheme_permissions: true
    allow_digest_with_kerberos: true
    plain_text_without_ssl: warn
    transitional_mode: disabled

When initially enabling authentication, specify the internal scheme as the default or other. After restarting DSE, to establish roles requires using the internal default cassandra account.

Table 1. authentication_options
Option	Description
auth_enabled	Turns on authentication using the default scheme.
default_scheme	Specifies the authentication scheme when not defined in the connection: * internal- Plain text authentication using internal login role with password, supply the role name and password as credentials. No additional configuration required. * ldap - Plain text authentication using pass-through LDAP authentication. See Defining an LDAP scheme. * kerberos - GSSAPI authentication using the Kerberos authenticator. See Defining a Kerberos scheme.
other_schemes	other_schemes
scheme_permissions	Validate that the role mapped to user matches the authentication scheme. Grant the role permission to the scheme.
allow_digest_with_kerberos	Allow Kerberos digest-md5 authentication.
plain_text_without_ssl	Handling of plain text connection requests: block - Block the request with an authentication error. warn - Log a warning but allow the request. allow - Allow the request without any warning.
transitional_mode	Sets the behavior when authentication fails and credentials are missing: disabled - Disable transitional mode. All connections must provide valid credentials and map to a login-enabled role. permissive - Only super users are authenticated and logged in. All other authentication attempts are logged in as the `anonymous` user. normal - Allow all connections that provide credentials. Maps all authenticated users to their role and maps all other connections to `anonymous`. strict - Allow only authenticated connections that map to a login-enabled role OR connections that provide a blank username and password as `anonymous`.

Configure the Kerberos options.

The options are located in the kerberos_options section.

Example:

kerberos_options:
   keytab: /etc/dse/dse.keytab
   service_principal: dse/_HOST@<REALM>
   http_principal: HTTP/_HOST@<REALM>
   qop: auth

Table 2. kerberos_options
Option	Description
keytab	The keytab file must contain the credentials for both of the fully resolved principal names, which replace `_HOST` with the Fully Qualified Domain Name (FQDN) of the host in the `service_principal` and `http_principal` settings. The UNIX user running DataStax Enterprise must also have read permissions on the keytab.
service_principal	Sets the principals name for the DSE database and DSE Search (Solr) processes. Use the form `dse/_HOST@REALM`, where `dse` is the service name. Leave `_HOST` as is. This variable is used in `dse.yaml`. DataStax Enterprise automatically substitutes the FQDN of the host where it runs. Credentials must exist for this principal in the keytab file and must be readable by the user that Cassandra runs as, usually `cassandra`. The `service_principal` must be consistent everywhere: `dse.yaml` file `keytab` `cqlshrc` file (where it is separated into the service/hostname)
http_principal	Used by the Tomcat application container to run DSE Search. The Tomcat web server uses the `GSSAPI mechanism (SPNEGO)` to negotiate the `GSSAPI security mechanism (Kerberos)`. `<REALM>` is the name of your Kerberos realm. In the Kerberos principal, `<REALM>` must be uppercase. Default: HTTP/_HOST@REALM
qop	A comma-delimited list of Quality of Protection (QOP) values that clients and servers can use for each connection. The client can have multiple QOP values, while the server can have only a single QOP value. The valid values are: `auth` - Default: Authentication only. `auth-int` - Authentication plus integrity protection for all transmitted data. `auth-conf` - Authentication plus integrity protection and encryption of all transmitted data. Encryption using `auth-conf` is separate and independent of whether encryption is done using SSL. If both `auth-conf` and SSL are enabled, the transmitted data is encrypted twice. DataStax recommends choosing only one method and using it for both encryption and authentication.

When adding a Kerberos scheme to an authentication enabled cluster, configure Kerberos roles before restarting DSE, see Setting up logins and users.

What is next

When initially configuring authentication, complete the set up by:

Performing a rolling restart.
Adding a superuser login.