Client installer by default tries to search for _ldap._tcp.DOMAIN DNS SRV records for all domains that are parent to its hostname. For example, if a client machine has a hostname client1.idm.example.com, the installer will try to retrieve an IdM server hostname from _ldap._tcp.idm.example.com, _ldap._tcp.example.com and _ldap._tcp.com DNS SRV records, respectively. The discovered domain is then used to configure client components (for example, SSSD and Kerberos 5 configuration) on the machine.

However, the hostnames of IdM clients are not required to be part of the primary DNS domain. If the client machine hostname is not in a subdomain of an IdM server, pass the IdM domain as the --domain option of the ipa-client-install command. In that case, after the installation of the client, both SSSD and Kerberos components will have the domain set in their configuration files and will use it to autodiscover IdM servers.

Additional resources

Identity Management (IdM) clients connect to a number of ports on IdM servers to communicate with their services.

On IdM client, these ports must be open in the outgoing direction. If you are using a firewall that does not filter outgoing packets, such as firewalld, the ports are already available in the outgoing direction.

Identity Management (IdM) does not require the IPv6 protocol to be enabled in the kernel of the host that you want to enroll into IdM. For example, if your internal network only uses the IPv4 protocol, you can configure the System Security Services Daemon (SSSD) to only use IPv4 to communicate with the IdM server. You can do this by inserting the following line into the [domain/NAME] section of the /etc/sssd/sssd.conf file:

lookup_family_order = ipv4_only

In RHEL8, the packages necessary for installing an Identity Management (IdM) client are shipped as a module. Two IdM streams provide IdM client packages: