How To Obtain and Deploy Keys and Certificates for TLS/SSL

Cloudera recommends obtaining certificates from one of the trusted public certificate authorities (CA) such as Symantec or Comodo for TLS/SSL encryption for the cluster. This How To provides a brief overview of the tools used to create the various artifacts followed by the steps in the process. Plan ahead to allow time to receive signed certificates from whichever CA you use.

If your organization uses its own internal CA, follow your internal process for creating and submitting the CSRs.

Continue reading:

Tools Overview

Java Keytool and OpenSSL are key management tools that let you create the security artifacts needed for TLS/SSL. See How to Convert PEM to JKS and JKS to PEM for TLS/SSL Services and Clients for more information beyond the two short overviews below.

Java Keytool

Oracle Java keytool is a utility included with the Oracle JDK for creating and managing cryptographic keys and certificates. During configuring the Cloudera Manager Cluster for TLS/SSL, you create the private key pairs, keystore, certificate signing requests, and create a truststore for specific use by the cluster using this software tool, as detailed in the steps throughout this guide.

Java Keytool Requirements for Cloudera Manager TLS/SSL Configuration

For any steps using the Java Keytool, be sure to:
  • Use the Oracle Java keytool rather than tools such as OpenJDK.
  • Use the JDK downloaded from Oracle or the Cloudera-provided Oracle JDK located in this default path on a Cloudera Manager Server host: 
    /usr/java/jdk1.7.0_67-cloudera/bin/jre/lib/security
  • Use the same version of the Java keytool for all steps. If the host has multiple JDKs installed, set the PATH variable so that the Oracle JDK is invoked first, as in this example: 
    $ export JAVA_HOME=/usr/java/jdk1.7.0_67-cloudera
$ export PATH=$JAVA_HOME/bin:$PATH
  • Use the same password for the -keypass and -storepass in any commands that invoke these two options. Cloudera Manager requires the same password for a key and its keystore.

OpenSSL

OpenSSL is an open source cryptography and TLS/SSL toolkit that has been widely used since its inception ~ 1999. Just as with Java Keytool, OpenSSL lets you create private keys, certificate requests, and keystores, and it provides options for verifying certificates.

Cloudera Manager Agent hosts act as clients of a Cloudera Manager Server host during RPC client and server communications. The Agent hosts, Hue, Impala and other Python-based services require PEM-formatted keys and certificates (PKCS #8), which is why the steps below include converting some of the JKS artifacts using this tool. See How to Convert PEM to JKS and JKS to PEM for TLS/SSL Services and Clients for more information.

Step 1: Create Directory for Security Artifacts

Distributing the certificates, keys, truststore—in short, all security artifacts used for TLS/SSL intra-cluster communications—is part of this and some subsequent processes. To keep things organized, Cloudera recommends that you create the directory and distribute and store artifacts when you receive them, even though they may not be immediately needed.

The following table shows an example directory structure for the security artifacts created in the steps in this and subsequent sections. Use different names if you like, but for ease of deployment, use the same directory names across all hosts in the cluster.

Example Description
cmhost.sec.example.com FQDN of an example Cloudera Manager Server host.
/opt/cloudera/security Base path for security-related files.
/opt/cloudera/security/pki Path for all security artifacts associated with TLS/SSL, including keys, keystores (keystore.jks), CSR, and root- and intermediate-CA certificates.
/usr/java/jdk1.7.0_67-cloudera/jre/lib/security/jssecacerts Path to the default alternative Java truststore on a Cloudera Manager Server host system.
  1. On the Cloudera Manager Server host, create the /opt/cloudera/security/pki directory: 
    $ sudo mkdir -p /opt/cloudera/security/pki
  2. This directory must be owned by cloudera-scm:cloudera-scm and have its executable bit set correctly so that Cloudera Manager can access the keystore at runtime: 
    $ sudo chown -R cloudera-scm:cloudera-scm /opt/cloudera/security/jks
$ umask 022
$ cd /opt/cloudera/security/jks

Directories and artifacts persist during system upgrades. For security purposes, for any host you remove from a cluster, remove any directories you create and more importantly, remove any security artifacts (keys, certificates, and so on) they may contain.

Step 2: Create the Java Truststore

On the Cloudera Manager Server host, copy the JDK cacerts file to jssecacerts: 
$ sudo cp $JAVA_HOME/jre/lib/security/cacerts $JAVA_HOME/jre/lib/security/jssecacerts

If you do not have the $JAVA_HOME variable set, replace it with the path to the Oracle JDK. For example, the default path to the Java JDK on a Cloudera Manager Server host is:

/usr/java/jdk1.7.0_67-cloudera/

Step 3: Generate Server Key and CSR

  1. On the Cloudera Manager Server host, use the keytool utility to generate a keypair and a keystore named for the server. Replace the OU, O, L, ST, and C entries with the values for your organization name, location, and country code (US, in the example): 
    $ sudo keytool -genkeypair -alias $(hostname -f)-server -keyalg RSA -keystore \
/opt/cloudera/security/pki/$(hostname -f)-server.jks -keysize 2048 -dname \
"CN=$(hostname -f),OU=Dept,O=Example.com,L=City,ST=State,C=US" \
-storepass password -keypass password
    Use the same password for the key and its keystore (-keypass and -storepass, respectively): Cloudera Manager does not support using different passwords for the key and keystore.
  2. Generate a certificate signing request (CSR) for the public key (contained in the keystore as a result of the command above). In this command below, enter the password that you set for the key and the keystore in the command above: 
    $ sudo keytool -certreq -alias $(hostname -f)-server \
-keystore /opt/cloudera/security/pki/$(hostname -f)-server.jks \
-file /opt/cloudera/security/pki/$(hostname -f)-server.csr -storepass password \
-keypass password

Step 4: Submit the CSR to the CA

  1. Submit the CSR file to your certificate authority using the process and means required by the CA, for example, email or web submission. For the certificate format, specify PEM (base64 ASCII) (see Step 5 below for an example of PEM formatted certificate heading and closing structure).
  2. The public CA will request specific details from you, to verify that you own the domain name contained in the CSR, before they issue the certificate.
  3. When you receive the signed certificate from the CA, you can proceed with Step 5.

Step 5: Verify the Certificate

From the public (or internal) CA, you receive the certificate for the server signed by the CA and several other digital artifacts, including root CA and possibly one (or more) intermediate CA certificates. Before distributing these to the hosts, make sure the certificate is in PEM format. A PEM formatted certificate file looks like this: 
-----BEGIN CERTIFICATE-----
<The encoded certificate is represented by multiple lines of exactly 64 characters, except
for the last line, which can contain 64 characters or fewer.>
-----END CERTIFICATE-----

If your issued certificate is in binary (DER) format, convert it to PEM format before continuing. See How to Convert Formats (PEM, JKS) for TLS/SSL Clients and Services for details.

To modify the truststore (jssecacerts) to explicitly trust certificates or certificate chain (as you might for certificates signed by an internal CA), follow the steps in How to Add Root and Intermediate CAs to Truststore for TLS/SSL.

Step 6: Import the Certificate into the Keystore

Copy the signed certificate you receive from the CA to the Cloudera Manager Server host. To identity the certificate's functionality, include a suffix such as "-server.cert.pem" in the target name for the copy command, as shown in this example: 
cp cert-file-recd /opt/cloudera/security/pki/$(hostname -f)-server.cert.pem
Import the certificate into the keystore. 
$ sudo keytool -importcert -alias $(hostname -f)-server \
-file /opt/cloudera/security/pki/$(hostname -f)-server.cert.pem \
-keystore /opt/cloudera/security/pki/$(hostname -f)-server.jks
Assuming the certificate was obtained from a public CA, you can safely disregard this message about trust, and enter yes to continue: 
... is not trusted. Install reply anyway? [no]:  yes
You must see the following response confirming that the certificate has been properly imported and can verify the private key that it certifies. 
Certificate reply was installed in keystore

If you do not see this response, double-check all your steps up to this point: are you working in the correct path? Do you have the proper certificate? and so on. See Getting Support for information about how to contact Cloudera Support and to find out about other sources of help if you cannot successfully import the certificates.