IdM uses the Kerberos protocol to support single sign-on. With Kerberos, users only need to present the correct username and password once and can access IdM services without the system prompting for credentials again.

The IdM internal LDAP directory server instance stores all IdM information, such as information related to Kerberos, user accounts, host entries, services, policies, DNS, and others.

The LDAP directory server instance is based on the same technology as Red Hat Directory Server. However, it is tuned to IdM-specific tasks.

The integrated Certificate Authority (CA) is based on the same technology as Red Hat Certificate System. pki is the Command-Line Interface for accessing Certificate System services.

For information relating to Red Hat Certificate System, a standalone Red Hat product, see Product Documentation for Red Hat Certificate System.

IdM uses DNS for dynamic service discovery. The IdM client installation utility can use information from DNS to automatically configure the client machine. After the client is enrolled in the IdM domain, it uses DNS to locate IdM servers and services within the domain.

The BIND (Berkeley Internet Name Domain) implementation of the DNS (Domain Name System) protocols in Red Hat Enterprise Linux includes the named DNS server. named-pkcs11 is a version of the BIND DNS server built with native support for the PKCS#11 cryptographic standard.

Many services require that servers and clients have the same system time, within a certain variance. For example, Kerberos tickets use time stamps to determine their validity and to prevent replay attacks. If the times between the server and client skew outside the allowed range, the Kerberos tickets are invalidated.

By default, IdM uses the Network Time Protocol (NTP) to synchronize clocks over a network via the ntpd service. With NTP, a central server acts as an authoritative clock and the clients synchronize their times to match the server clock. The IdM server is configured as the NTP server for the IdM domain during the server installation process.

The Apache HTTP web server provides the IdM Web UI, and also manages communication between the Certificate Authority and other IdM services.

Samba implements the Server Message Block (SMB) protocol, also known as the Common Internet File System (CIFS) protocol), in Red Hat Enterprise Linux. Via the smb service, the SMB protocol enables you to access resources on a server, such as file shares and shared printers. If you have configured a Trust with an Active Directory (AD) environment, the Winbind service manages communication between IdM servers and AD servers.

One-time passwords (OTP) are passwords that are generated by an authentication token for only one session, as part of two-factor authentication. OTP authentication is implemented in Red Hat Enterprise Linux via the ipa-otpd service.

Custodia is a Secrets Services provider, it stores and shares access to secret material such as passwords, keys, tokens, certificates.

OpenDNSSEC is a DNS manager that automates the process of keeping track of DNS security extensions (DNSSEC) keys and the signing of zones. The ipa-dnskeysyncd servuce manages synchronization between the IdM Directory Server and OpenDNSSEC.

The System Security Services Daemon (SSSD) is the client-side application that manages user authentication and caching credentials.

Caching enables the local system to continue normal authentication operations if the IdM server becomes unavailable or if the client goes offline.

For more information about SSSD, see the System-Level Authentication Guide. SSSD also supports Windows Active Directory (AD). For more information about using SSSD with AD, see the Windows Integration Guide.

The certmonger service monitors and renews the certificates on the client. It can request new certificates for the services on the system.

For more information about certmonger, see the System-Level Authentication Guide.