If you have enabled Kerberos authentication for Greenplum Database, you can set up Greenplum Command Center to accept connections from Kerberos-authenticated users.
Greenplum Database and Command Center include support for the Generic Security Service Applications Program Interface (GSS-API) standard. A related standard, Simple and Protected GSS-API Negotiation Mechanism (SPNEGO), describes the protocol GSS-API clients and servers use to agree on the method of authentication.
With a SPNEGO-compliant web application such as Command Center, the client and server agree on the authentication method on the client's initial HTTP request. If Kerberos authentication is not supported on both ends of the connection the server falls back to basic authentication, and displays a login form requesting a user name and password. If a user has authenticated on the workstation with Kerberos and has a valid ticket granting ticket, the web browser offers the user's credential to the Command Center web server. A Kerberos-enabled Command Center web server is configured to handle the authenticated user's connection request in one of three modes, called strict, normal, or gpmon-only.
Command Center has a Kerberos keytab file containing the Command Center service principal and a principal for every Command Center user. If the principal in the client's connection request is in the keytab file, the web server grants the client access and the web server connects to Greenplum Database using the client's principal name. If the principal is not in the keytab file, the connection request fails.
The Command Center Kerberos keytab file contains the Command Center principal and may contain principals for Command Center users. If the principal in the client's connection request is in Command Center's keytab file, it uses the client's principal for database connections. Otherwise, Command Center uses the gpmon user for database connections.
Command Center uses the gpmon database role for all Greenplum Database connections. No client principals are required in the Command Center’s keytab file. This option can be used, for example, if Command Center users authenticate with Active Directory and you do not want to maintain client principals in the keytab file.
If you have set up Kerberos authentication for Greenplum Database, most of the configuration required to enable Command Center Kerberos authentication has been done. The Command Center Kerberos configuration builds upon the Greenplum Database Kerberos setup.
Kerberos authentication can be enabled by responding to prompts when you install Command Center, or you can use the
gpcc --krbenable command to enable Kerberos after Command Center has been installed.
Kerberos authentication must be enabled for Greenplum Database. See Using Kerberos Authentication for instructions. Make sure the following prerequisites are met before you continue:
krb5-workstationpackage and associated libraries (
libkrb5*) must be installed on the Greenplum master host and each client workstation.
krb5.confconfiguration file must be the same on the KDC host, the Greenplum Database master host, and client workstations.
postgres/<master-host>@<realm>. You can choose a service name other than
postgres, but it must match the value of the
krb_srvnameparameter in the
krb_server_keyfileparameter in the
Before you configure Command Center for Kerberos authentication, you must create the required Kerberos principals. All of the principals used with Command Center are created in the Greenplum Database Kerberos realm. Command Center users can use the same Kerberos principal to authenticate with Command Center and Greenplum Database.
Command Center Service Principal
A service principal is needed for the Command Center web server. This principal has the format
HTTP/<host>@<realm>. For example, if users access Command Center at the URL
<host> part of the service key is
mdw.example.com and the
<realm> part is the Greenplum Database Kerberos realm, for example
Note that Kerberos authentication only works if Command Center users enter the host in the same format specified in the Kerberos service principal. If the principal specifies the FQDN, for example, using the host's IP address in the browser URL will not work; the web server will fall back to basic authentication.
Greenplum Database gpmon User
Command Center uses the gpmon Greenplum role to access the gpperfmon database, which contains data presented in the Command Center UI.
You can choose to authenticate the gpmon user with Kerberos or with basic authentication. To use Kerberos, you must create a principal for the gpmon user.
If you choose to use basic authentication you do not need a Kerberos principal for the gpmon user. The gpmon user will authenticate with Greenplum Database using the password saved in the
.pgpass file in the gpadmin user's home directory on the host running Command Center. If you run Command Center on a host other than the Greenplum Database master host, you must copy the
.pgpass file from the master host to the Command Center host. See Changing the gpmon Password for instructions to manage the gpmon password.
Command Center Users
Add Kerberos principals for any Command Center users who do not already have principals in the KDC for Greenplum Database.
To add the required principals, perform the following steps as root on the KDC server.
Add a principal for the Command Center web service. Be sure to specify the
<gpcc-host> in the same format that users should enter the host in their browsers.
# kadmin.local -q "addprinc -randkey HTTP/<gpcc-host>@<realm>"
If you want the gpmon database user to use Kerberos authentication, add a gpmon principal.
# kadmin.local -q "addprinc gpmon@<realm>"
Add principals for any new Command Center users.
# kadmin.local -q "addprinc cc_user1@<realm>"
Repeat for each new Command Center user.
After you have created all of the Kerberos principals needed, you create and distribute keytab files. Keytab files contain Kerberos principals and encrypted keys based on the principals' Kerberos passwords. Keytab files are needed for the Greenplum Database master and standby hosts and the Command Center host.
You can also create a keytab file for each Greenplum Database or Command Center user containing just the user's principal. This keytab file is installed on the user's workstation to enable the user to authenticate to Kerberos. Note that all keytab files must contain the most recent versions of the principals' keys.
If the Greenplum Command Center web server is running on the Greenplum Database master host, Command Center can share the Greenplum Database keytab file. You need to create a keytab file that contains the following principals:
postgresprocess on the Greenplum Database master host, for example
All service keys and principals should be in the Greenplum Database realm.
To create a keytab file for Greenplum Database and Command Center, perform the following steps as root on the KDC server.
Create a keytab file containing the Greeplum Database service key, the command center service key, and all database and Command Center users.
kadmin.local -q "ktadd -k gpdb-kerberos.keytab postgres/mdw.example.com@GPDB.KRB HTTP/mdw.example.com@GPDB.KRB"
You can enter one or more principals with each
ktadd command. You can specify a wildcard using the
-glob option. For example this command adds all principals in the
GPDB.KRB realm, including service principals and admin users.
kadmin.local -q "ktadd -k gpdb-kerberos.keytab -glob *@GPDB.KRB"
Copy the keytab you created to the Greenplum Database master host, replacing the old keytab file. The location of the file is given by the
krb_server_keyfile parameter in the
$MASTER_DATA_FILE/postgresql.conf file. Set the permissions on the file so that it can be read only by the gpadmin user.
Update any entries required for new Greenplum Database principals in the
pg_hba.conf file and
pg_ident.conf files. See Update the Greenplum Database
pg_hba.conf File for details.
If the Command Center web server is on a different host than the Greenplum Database master, you need separate keytab files for Greenplum Database and Command Center. The keytab file for Greenplum Database may not require any updates, but you will need to create a keytab file for Command Center.
Update the Greenplum Database keytab if you created new database roles and principals for Command Center. For example, if you want to use Kerberos authentication for the gpmon user, you must create a principal and add it to both the Greenplum Database and Command Center keytab files.
To create the keytab file for Command Center, perform the following steps as root on the KDC host.
Create a keytab file and add the Command Center service key.
kadmin.local -q "ktadd -k gpcc-kerberos.keytab HTTP/smdw.example.com@GPDB.KRB"
If you want to authenticate the gpmon user with Kerberos, add the gpmon principal.
kadmin.local -q "ktadd -k gpcc-kerberos.keytab gpmon@GPDB.KRB"
Add principals for all Command Center users:
kadmin.local -q "ktadd -k gpcc-kerberos.keytab cc_user1@GPDB.KRB cc_user2@GPDB.KRB"
You can enter one or more principals with each
quit to exit
Copy the keytab you created to the the host running Command Center, for example:
$ scp gpcc-kerberos.keytab gpadmin@<host-name>:/home/gpadmin
Update any entries required for new principals in the
pg_hba.conf file and
pg_ident.conf files on the Greenplum master. See Update the Greenplum Database pg_hba.conf File.
The Greenplum Database
$MASTER_DATA_DIRECTORY/pg_hba.conf configuration file determines which authentication methods to use to allow database access.
If you created new Command Center users, you may need to add an entry to allow access via Command Center. The entry for an individual user has this format:
host database <user-name> <gpcc CIDR> gss [options]
Authentication for the gpmon user needs to be set up in the
pg_hba.conf file in one of the following ways.
/home/gpadmin/.pgpass file contains the password for gpmon to use. See Changing the gpmon Password for details. An entry in the
pg_hba.conf file specifies the md5 authentication method for gpmon:
local all gpmon md5
On the Greenplum Database master host only, the gpmon user can access databases without authentication:
local all gpmon trust
/home/gpadmin/.pgpass file is not needed.
A Kerberos principal has been created for the gpmon user and added to the Greenplum Database and Command Center keytab files.
host all gpmon <gpcc CIDR> gss [options]
Remove any existing reject rules for gpmon:
host all gpmon <auth-method> reject
See Using Kerberos Authentication for more information about the
Set up Command Center to use the Command Center keytab file you created.
If you are adding Kerberos authentication to an existing Command Center, use the
gpcc command. For example:
$ gpcc --krbenable
Enter the Command Center host name and path to the keytab file at the prompts. See the gpcc Reference for more information.
To use Kerberos Command Center authentication, the user must have authenticated with Kerberos using the
kinit command-line tool.
The user then accesses the Command Center web server with a URL containing the host name in the format specified in the Command Center service principal and the port number, for example
The user's web browser must be configured to use the SPNEGO protocol so that it offers the user's Kerberos principal to the web browser. The method for configuring web browsers varies with different browsers and operating systems. Search online to find instructions to enable SPNEGO with your browser and OS.