Configuring Kerberos Authentication Using Local KDC and Active Directory KDC
The Big Data Service cluster provisions local MIT KDC by default. The cluster can be also be provisioned to use Active Directory KDC for users belonging to the Active Directory domain. You must also requires setting up cross trust between the two realms.
Updating Ambari to Use Active Directory KDC
Login to the Ambari UI associated with your Big Data Service cluster.
From the left navigation menu, under Services click Kerberos.
Click the Configs tab and then expand the Advanced krb5-conf section.
Modify the krb5-conf template field similar to the following content:
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[libdefaults]
renew_lifetime = 7d
forwardable = true
default_realm = {{realm}}
ticket_lifetime = 24h
dns_lookup_realm = false
dns_lookup_kdc = false
#default_ccache_name = /tmp/krb5cc_%{uid}
#default_tgs_enctypes = {{encryption_types}}
#default_tkt_enctypes = {{encryption_types}}
{% if domains %}
[domain_realm]
{%- for domain in domains.split(',') %}
{{domain|trim()}} = {{realm}}
{%- endfor %}
{% endif %}
example.oraclevcn.com = <ad-realm>
[logging]
default = FILE:/var/log/krb5kdc.log
admin_server = FILE:/var/log/kadmind.log
kdc = FILE:/var/log/krb5kdc.log
[realms]
{{realm}} = {
{%- if master_kdc %}
master_kdc = {{master_kdc|trim()}}
{%- endif -%}
{%- if kdc_hosts > 0 -%}
{%- set kdc_host_list = kdc_hosts.split(',') -%}
{%- if kdc_host_list and kdc_host_list|length > 0 %}
admin_server = {{admin_server_host|default(kdc_host_list[0]|trim(), True)}}
{%- if kdc_host_list -%}
{%- if master_kdc and (master_kdc not in kdc_host_list) %}
kdc = {{master_kdc|trim()}}
{%- endif -%}
{% for kdc_host in kdc_host_list %}
kdc = {{kdc_host|trim()}}
{%- endfor -%}
{% endif %}
{%- endif %}
{%- endif %}
}
{# Append additional realm declarations below #}
<ad-realm> = {
admin_server = server-example.oraclevcn.com:749
kdc = kdc-example.oraclevcn.com:88
default_domain = domain-example.oraclevcn.com
}
[capaths]
<ad-realm> = {
<your-local-realm> = .
}
Save the configuration and restart all the affected services.
Navigate to HDFS > Configs > Advanced > Advanced core-site.
Change the hadoop.security.auth_to_local parameter to include the following:
You can set up a one-way cross-realm trust from a local Key Distribution Center (KDC) to the Active Directory realm in a Big Data Service ODH kerberos enabled cluster.
Configuring the Active Directory Server 🔗
To set the preferred encrption type in the Active Directory (AD) server, open the Group Policy Management dialog (Start > Windows Administrative ToolsGroup Policy Management).
In the Group Policy Management dialog, navigate to the Forest: <ad-realm> > Domains > <ad-realm> folder.
Right-click Default Domain Policy and select Edit.
In the Group Policy Management Editor, navigate to Security Options by explanding Computer Configuration > Policies > Windows Settings > Security Settings > Local Policies > Security Options.
Ensure that the Security Options folder is selected and then double-click policy Network security: Configure encryption types allowed for Kerberos.
Configure the required encryption type allowed for Kerberos from the dialogue box. We recommend using the strongest encryption type supported on Big Data Service, which is AES256_HMAC_SHA1. Select the policy and then click OK.
Set the encryption on the command line by adding the local realm trust to Active Directory.
You're prompted to enter a password. Use the same password you used in the netdom command on the Active Directory server.
Example:
kadmin.local: addprinc -e "aes256-cts:normal" krbtgt/<EXAMPLE_USER>@<EXAMPLE.REALM>
> WARNING: no policy specified for krbtgt/<EXAMPLE_USER>@<EXAMPLE.REALM>; defaulting to no policy
> Enter password for principal "krbtgt/<EXAMPLE_USER>@<EXAMPLE.REALM>":
> Re-enter password for principal "krbtgt/<EXAMPLE_USER>@<EXAMPLE.REALM>":
> Principal "krbtgt/<EXAMPLE_USER>@<EXAMPLE.REALM>" created.
Note
The encryption type on Big Data Service has a different naming convention than on the Active Directory server. For example, if AES256-CTS-HMAC-SHA1-96 is used on the Active Directory server, the corresponding type on Big Data Service is aes256-cts:normal.