# Configuration of JAAS Authentication

You can configure the Central Administration server to use Java Authentication and Authorization Service (JAAS) authentication. JAAS authentication has two purposes:

- Authenticate users logging into the Central Administration server.

  When JAAS is configured, users must enter credentials when logging into the Central Administration web interface. Central Administration users must be in one of these JAAS groups:

  - `emsca-admin` — Grants administrative privileges to members. Administrators may lock and edit an EMS server in Central Administration, and deploy an updated server configuration. However, note that the user must also have administrative privileges for the EMS server before deploying.

    You can change the group names with administrative privileges using the `--jaas-admin` option.

  - `emsca-guest` — Grants read-only privileges to members. Guest users are not able to make changes or deploy configurations through Central Administration.

    You can change the group names with guest privileges using the `--jaas-guests` option.

- Authenticate the Central Administration server to EMS servers.

  When JAAS is configured, each time a user attempts to add or refresh an EMS server or deploy configuration changes, the Central Administration server uses the JAAS user ID and password presented by the user to authenticate with the EMS server. If the user does not have sufficient privileges, the action fails.

Warning: When using JAAS, you should not create a user name that has the same name as a JAAS group. Depending on the JAAS implementation, it is possible for a user name matching a group name to be included in the group.

Additionally, assigning conflicting JAAS roles (such as guest and admin) to the same user grants admin privileges.

To enable JAAS authentication, set the `--jaas` option at the command line, or through the related setting in the Central Administration configuration file.

JAAS can be configured to fetch user credentials from a property file or from an LDAP server. With LDAP, changes made to Central Administration user credentials are taken into account dynamically. With a property file, it is required to restart the Central Administration server upon altering user credentials.

For more information on JAAS security, see the sample configuration files in EMS_HOME\samples\emsca\jaas.

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