(Optional) Install a new MIT KDC

The following gives a very high level description of the KDC installation process.

	Note
	Because Kerberos is a time-sensitive protocol, all hosts in the realm must be time-synchronized, for example, by using the Network Time Protocol (NTP). If the local system time of a client differs from that of the KDC by as little as 5 minutes (the default), the client will not be able to authenticate.

Install the KDC Server

Install a new version of the KDC server:
RHEL/CentOS/Oracle Linux
yum install krb5-server krb5-libs krb5-workstation
SLES
zypper install krb5 krb5-server krb5-client
Ubuntu/Debian
apt-get install krb5-kdc krb5-admin-server
Using a text editor, open the KDC server configuration file, located by default here:
vi /etc/krb5.conf
Change the [realms] section of this file by replacing the default “kerberos.example.com” setting for the kdc and admin_server properties with the Fully Qualified Domain Name of the KDC server host. In the following example, “kerberos.example.com” has been replaced with “my.kdc.server”.
```
[realms]
 EXAMPLE.COM = {
   kdc = my.kdc.server
   admin_server = my.kdc.server
}
```
Some components such as HUE require renewable tickets. To configure MIT KDC to support them, ensure the following settings are specified in the libdefaults section of the /etc/krb5.conf file.
renew_lifetime = 7d

	Note
	For Ubuntu/Debian, the setup of the default realm for the KDC and KDC Admin hostnames is performed during the KDC server install. You can re-run setup using dpkg-reconfigure krb5-kdc. Therefore, Steps 2 and 3 above are not needed for Ubuntu/Debian.

Create the Kerberos Database

Use the utility kdb5_util to create the Kerberos database.

RHEL/CentOS/Oracle Linux

kdb5_util create -s

SLES

kdb5_util create -s

Ubuntu/Debian

krb5_newrealm

Start the KDC

Start the KDC server and the KDC admin server.

RHEL/CentOS/Oracle Linux 6

/etc/rc.d/init.d/krb5kdc start

/etc/rc.d/init.d/kadmin start

RHEL/CentOS/Oracle Linux 7

systemctl start krb5kdc

systemctl start kadmin

SLES

rckrb5kdc start

rckadmind start

Ubuntu/Debian

service krb5-kdc restart

service krb5-admin-server restart

	Important
	When installing and managing your own MIT KDC, it is very important to set up the KDC server to auto-start on boot . For example: RHEL/CentOS/Oracle Linux 6 `chkconfig krb5kdc on` `chkconfig kadmin on` RHEL/CentOS/Oracle Linux 7 `systemctl enable krb5kdc` `systemctl enable kadmin` SLES `chkconfig rckrb5kdc on` `chkconfig rckadmind on`

Create a Kerberos Admin

Kerberos principals can be created either on the KDC machine itself or through the network, using an “admin” principal. The following instructions assume you are using the KDC machine and using the kadmin.local command line administration utility. Using kadmin.local on the KDC machine allows you to create principals without needing to create a separate "admin" principal before you start.

	Note
	You will need to provide these admin account credentials to Ambari when enabling Kerberos. This allows Ambari to connect to the KDC, create the cluster principals and generate the keytabs.

Create a KDC admin by creating an admin principal.
kadmin.local -q "addprinc admin/admin"
Confirm that this admin principal has permissions in the KDC ACL. Using a text editor, open the KDC ACL file:
RHEL/CentOS/Oracle Linux
vi /var/kerberos/krb5kdc/kadm5.acl
SLES
vi /var/lib/kerberos/krb5kdc/kadm5.acl
Ubuntu/Debian
vi /etc/krb5kdc/kadm5.acl
Ensure that the KDC ACL file includes an entry so to allow the admin principal to administer the KDC for your specific realm. When using a realm that is different than EXAMPLE.COM, be sure there is an entry for the realm you are using. If not present, principal creation will fail. For example, for an admin/admin@HADOOP.COM principal, you should have an entry:
*/admin@HADOOP.COM *
After editing and saving the kadm5.acl file, you must restart the kadmin process.
RHEL/CentOS/Oracle Linux 6
/etc/rc.d/init.d/kadmin restart
RHEL/CentOS/Oracle Linux 7
systemctl restart kadmin
SLES
rckadmind restart
Ubuntu/Debian
service krb5-admin-server restart