# Presto 316 Documentation

## 3.4. Java Keystores and Truststores

## Java Keystore File for TLS

Access to the Presto coordinator must be through HTTPS when using Kerberos and LDAP authentication. The Presto coordinator uses a Java Keystore file for its TLS configuration. These keys are generated using keytool and stored in a Java Keystore file for the Presto coordinator.

The alias in the keytool command line should match the principal that the Presto coordinator will use.

You’ll be prompted for the first and last name. Use the Common Name that will be used in the certificate. In this case, it should be the unqualified hostname of the Presto coordinator. In the following example, you can see this in the prompt that confirms the information is correct:

    keytool -genkeypair -alias presto -keyalg RSA -keystore keystore.jks
    Enter keystore password:
    Re-enter new password:
    What is your first and last name?
      [Unknown]:  presto-coordinator.example.com
    What is the name of your organizational unit?
      [Unknown]:
    What is the name of your organization?
      [Unknown]:
    What is the name of your City or Locality?
      [Unknown]:
    What is the name of your State or Province?
      [Unknown]:
    What is the two-letter country code for this unit?
      [Unknown]:
    Is CN=presto-coordinator.example.com, OU=Unknown, O=Unknown, L=Unknown, ST=Unknown, C=Unknown correct?
      [no]:  yes

    Enter key password for <presto>
            (RETURN if same as keystore password):

## Java Truststore File for TLS

Truststore files contain certificates of trusted TLS/SSL servers, or of Certificate Authorities trusted to identify servers. For securing access to the Presto coordinator through HTTPS the clients can configure truststores. For the Presto CLI to trust the Presto coordinator, the coordinator’s certificate must be imported to the CLI’s truststore.

You can either import the certificate to the default Java truststore, or to a custom truststore. You should be careful if you choose to use the default one, since you may need to remove the certificates of CAs you do not deem trustworthy.

You can use keytool to import the certificate to the truststore. In the example, we are going to import `presto_certificate.cer` to a custom truststore `presto_trust.jks`, and you will get a prompt asking if the certificate can be trusted or not.

    $ keytool -import -v -trustcacerts -alias presto_trust -file presto_certificate.cer -keystore presto_trust.jks -keypass <truststore_pass>

## Troubleshooting

### Java Keystore File Verification

Verify the password for a keystore file and view its contents using keytool.

    $ keytool -list -v -keystore /etc/presto/presto.jks