KrbServer and LdapServer Principles

Overview

To manage the access control permissions on data and resources in a cluster, it is recommended that the cluster be installed in security mode. In security mode, a client application must be authenticated and a secure session must be established before the application accesses any resource in the cluster. MRS uses KrbServer to provide Kerberos authentication for all components, implementing a reliable authentication mechanism.

LdapServer supports Lightweight Directory Access Protocol (LDAP) and provides the capability of storing user and user group data for Kerberos authentication.

Architecture

The security authentication function for user login depends on Kerberos and LDAP.

Figure 1 Security authentication architecture

Figure 1 includes three scenarios:

Logging in to the MRS Manager Web UI
The authentication architecture includes steps 1, 2, 3, and 4.
Logging in to a component web UI
The authentication architecture includes steps 5, 6, 7, and 8.
Accessing between components
The authentication architecture includes step 9.

**Table 1** Key modules
Connection Name	Description
Manager	Cluster Manager
Manager WS	WebBrowser
Kerberos1	KrbServer (management plane) service deployed in MRS Manager, that is, OMS Kerberos
Kerberos2	KrbServer (service plane) service deployed in the cluster
LDAP1	LdapServer (management plane) service deployed in MRS Manager, that is, OMS LDAP
LDAP2	LdapServer (service plane) service deployed in the cluster

Data operation mode of Kerberos1 in LDAP: The active and standby instances of LDAP1 and the two standby instances of LDAP2 can be accessed in load balancing mode. Data write operations can be performed only in the active LDAP1 instance. Data read operations can be performed in LDAP1 or LDAP2.

Data operation mode of Kerberos2 in LDAP: Data read operations can be performed in LDAP1 and LDAP2. Data write operations can be performed only in the active LDAP1 instance.

Principle

Kerberos authentication

Figure 2 Authentication process

LDAP data read and write

Figure 3 Data modification process

LDAP data synchronization

OMS LDAP data synchronization before cluster installation
Figure 4 OMS LDAP data synchronization

Data synchronization direction before cluster installation: Data is synchronized from the active OMS LDAP to the standby OMS LDAP.
LDAP data synchronization after cluster installation
Figure 5 LDAP data synchronization

Data synchronization direction after cluster installation: Data is synchronized from the active OMS LDAP to the standby OMS LDAP, standby component LDAP, and standby component LDAP.