3.3. LDAP Authentication

Presto can be configured to enable frontend LDAP authentication overHTTPS for clients, such as the Presto CLI, or the JDBC and ODBCdrivers. At present only simple LDAP authentication mechanism involvingusername and password is supported. The Presto client sends a usernameand password to the coordinator and coordinator validates thesecredentials using an external LDAP service.

To enable LDAP authentication for Presto, configuration changes are made onthe Presto coordinator. No changes are required to the worker configuration;only the communication from the clients to the coordinator is authenticated.However, if you want to secure the communication betweenPresto nodes with SSL/TLS configure Secure Internal Communication.

Presto Server Configuration

Environment Configuration

Secure LDAP

Presto requires Secure LDAP (LDAPS), so make sure you have TLSenabled on your LDAP server.

TLS Configuration on Presto Coordinator

You need to import the LDAP server’s TLS certificate to the default Javatruststore of the Presto coordinator to secure TLS connection. You can usethe following example keytool command to import the certificateldap_server.crt, to the truststore on the coordinator.

$ keytool -import -keystore <JAVA_HOME>/jre/lib/security/cacerts -trustcacerts -alias ldap_server -file ldap_server.crt

In addition to this, access to the Presto coordinator should bethrough HTTPS. You can do it by creating a Java Keystore File for TLS onthe coordinator.

Presto Coordinator Node Configuration

You must make the following changes to the environment prior to configuring thePresto coordinator to use LDAP authentication and HTTPS.

• Secure LDAP
• Java Keystore File for TLS

You also need to make changes to the Presto configuration files.LDAP authentication is configured on the coordinator in two parts.The first part is to enable HTTPS support and password authenticationin the coordinator’s config.properties file. The second part isto configure LDAP as the password authenticator plugin.

Server Config Properties

The following is an example of the required properties that need to be addedto the coordinator’s config.properties file:

http-server.authentication.type=PASSWORD
 
http-server.https.enabled=true
http-server.https.port=8443
 
http-server.https.keystore.path=/etc/presto_keystore.jks
http-server.https.keystore.key=keystore_password

Password Authenticator Configuration

Password authentication needs to be configured to use LDAP. Create anetc/password-authenticator.properties file on the coordinator. Example:

password-authenticator.name=ldap
ldap.url=ldaps://ldap-server:636
ldap.user-bind-pattern=<Refer below for usage>

Based on the LDAP server implementation type, the propertyldap.user-bind-pattern can be used as described below.

Active Directory

ldap.user-bind-pattern=${USER}@<domain_name_of_the_server>

Example:

ldap.user-bind-pattern=${USER}@corp.example.com

OpenLDAP

ldap.user-bind-pattern=uid=${USER},<distinguished_name_of_the_user>

Example:

ldap.user-bind-pattern=uid=${USER},OU=America,DC=corp,DC=example,DC=com

Authorization based on LDAP Group Membership

You can further restrict the set of users allowed to connect to the Prestocoordinator based on their group membership by setting the optionalldap.group-auth-pattern and ldap.user-base-dn properties in additionto the basic LDAP authentication properties.

Based on the LDAP server implementation type, the propertyldap.group-auth-pattern can be used as described below.

Active Directory

ldap.group-auth-pattern=(&(objectClass=<objectclass_of_user>)(sAMAccountName=${USER})(memberof=<dn_of_the_authorized_group>))

Example:

ldap.group-auth-pattern=(&(objectClass=person)(sAMAccountName=${USER})(memberof=CN=AuthorizedGroup,OU=Asia,DC=corp,DC=example,DC=com))

OpenLDAP

ldap.group-auth-pattern=(&(objectClass=<objectclass_of_user>)(uid=${USER})(memberof=<dn_of_the_authorized_group>))

Example:

ldap.group-auth-pattern=(&(objectClass=inetOrgPerson)(uid=${USER})(memberof=CN=AuthorizedGroup,OU=Asia,DC=corp,DC=example,DC=com))

For OpenLDAP, for this query to work, make sure you enable thememberOf overlay.

You can also use this property for scenarios where you want to authorize a userbased on complex group authorization search queries. For example, if you want toauthorize a user belonging to any one of multiple groups (in OpenLDAP), thisproperty may be set as follows:

ldap.group-auth-pattern=(&(|(memberOf=CN=normal_group,DC=corp,DC=com)(memberOf=CN=another_group,DC=com))(objectClass=inetOrgPerson)(uid=${USER}))

Presto CLI

Environment Configuration

TLS Configuration

Access to the Presto coordinator should be through HTTPS when using LDAPauthentication. The Presto CLI can use either a Java Keystore file or Java Truststorefor its TLS configuration.

If you are using keystore file, it can be copied to the client machine and usedfor its TLS configuration. If you are using truststore, you can either usedefault java truststores or create a custom truststore on the CLI. We do notrecommend using self-signed certificates in production.

Presto CLI Execution

In addition to the options that are required when connecting to a Prestocoordinator that does not require LDAP authentication, invoking the CLIwith LDAP support enabled requires a number of additional command lineoptions. You can either use —keystore- or —truststore- propertiesto secure TLS connection. The simplest way to invoke the CLI is with awrapper script.

#!/bin/bash
 
./presto \
--server https://presto-coordinator.example.com:8443 \
--keystore-path /tmp/presto.jks \
--keystore-password password \
--truststore-path /tmp/presto_truststore.jks \
--truststore-password password \
--catalog <catalog> \
--schema <schema> \
--user <LDAP user> \
--password

Troubleshooting

Java Keystore File Verification

Verify the password for a keystore file and view its contents usingJava Keystore File Verification.

SSL Debugging for Presto CLI

If you encounter any SSL related errors when running Presto CLI, you can run CLI using -Djavax.net.debug=sslparameter for debugging. You should use the Presto CLI executable jar to enable this. Eg:

java -Djavax.net.debug=ssl \
-jar \
presto-cli-<version>-executable.jar \
--server https://coordinator:8443 \
<other_cli_arguments>

Common SSL errors

java.security.cert.CertificateException: No subject alternative names present

This error is seen when the Presto coordinator’s certificate is invalid and does not have the IP you providein the —server argument of the CLI. You will have to regenerate the coordinator’s SSL certificatewith the appropriate SAN added.

Adding a SAN to this certificate is required in cases where https:// uses IP address in the URL ratherthan the domain contained in the coordinator’s certificate, and the certificate does not contain theSAN parameter with the matching IP address as an alternative attribute.