KrbServer and LdapServer Principles

Overview

To manage the access control permissions on data and resources in a cluster, it is recommended that the cluster in security mode be installed. 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.

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

Kerberos is a security authentication system designed with the client/server architecture that employs encryption technologies such as DES and AES. The system supports mutual authentication, that is, the client and server can authenticate identity of each other. Kerberos prevents interception and replay attacks, and protects data integrity. It manages keys by using a symmetric key mechanism.

Kerberos authentication consists of the following roles:

• Client
• Server
• Key Distribution Center (KDC): consists of the Authentication Server (AS) and Ticket Granting Server (TGS).
  • AS verifies the client account and password and generates a Ticket Granting Ticket (TGT).
  • TGS generates Service Tickets (STs) for accessing services based on TGTs.

Figure 2 Authentication process

LDAP data read and write

LDAP serves as a user data storage center and stores user information (such as passwords and supplementary information) in the cluster. Users need to access LDAP to operate user data or perform Kerberos authentication.

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.