Configure API Gateway for IBM MQ Server TLS

Describes how to configure API Gateway to securely connect using TLS to an IBM MQ server and keep up with changes by IBM on the server side, including how to configure TLS communication on API Gateway for different IBM MQ server versions.

8 minute read

Integration with IBM MQ

One of the core components of AMPLIFY API Management is the API Gateway. API Gateway ships with support for several third-party systems for easier integrations. API Gateway is acting as a client requesting services from an external provider. One of those built-in features is support for the messaging system IBM MQ. IBM MQ is a widely used enterprise message communication service that often powers complex and mission critical services for large enterprises.

API Gateway is built on Java and uses Java message service (JMS) for messaging. Connecting to JMS servers requires some general configuration and special settings:

  • To configure the connection to a JMS server, see Configure messaging services.
  • To listen on queues or topics for messages to process, configure a JMS service provider (listener) as detailed in Configure a JMS session.
  • For writing received and processed messages to queues or topics and waiting for reply messages from back-end services, see Route to JMS filters.

Different vendors have different strategies to maintain compatibility between messaging clients and JMS servers. IBM offers backward compatibility for some versions of MQ clients as described in IBM Support, MQ 7.x, MQ 8.0, MQ 9.0 and MQ 9.1 compatibility with previous versions.

This means that client programs can use older connectivity libraries to connect to newer versions of the MQ servers. This enables you to decouple lifetime or maintenance cycles of client applications from a currently used MQ server. However, for securing the communication using TLS all clients need to support a minimum TLS version and a defined set of TLS ciphers defined by the MQ server. If a MQ client uses a cipher that is not on the supported list of ciphers for the IBM MQ server channel, the TLS handshake will fail with the error MQRC_UNSUPPORTED_CIPHER_SUITE.

Several AMPLIFY API Management customers were facing the challenge to connect API Gateway to an upgraded IBM MQ server, and reconfigure the IBM MQ client settings within Policy Studio for this change, and the following sections describe the background and steps for how best to accomplish this.

Configure API Gateway for TLS with IBM MQ Server

API Gateway is acting as client connecting to an IBM MQ server and it bundles the IBM MQ JMS and Java redistributable client within the API Gateway installation (for example, API Gateway up to v7.7.20200130 bundles IBM MQ client v7.5.0.8). Later versions of IBM MQ server (for example, 9.1.5 is used here) still allow those clients to connect, but have more strict requirements on TLS.

Adapt the basic setup within Policy Studio for IBM MQ server connectivity as follows:

  1. Follow the steps in Configure messaging services for IBM MQ.

    The following shows the JMS service configuration wizard: MQ JMS Service

  2. In the JMS wizard, for the Service type IBM MQ, change the cipher suite name to one of the ciphers suites supported by your MQ server. This example uses TLS_RSA_WITH_AES_128_CBC_SHA256 and TLS_RSA_WITH_AES_256_CBC_SHA256. The supported ciphers are subject to the ones available within the JVM that API Gateway is running on.

    The cipher suite names differ between different vendors of JVMs. API Gateway comes with a JVM that uses the Oracle naming conventions. For details, see SSL/TLS CipherSpecs and CipherSuites in IBM MQ classes for JMS.

    An MQ client must signal one specific cipher suite it intends to use to the MQ server. The best fitting one of the configured ciphers suites of the IBM MQ channel needs to be selected upfront and configured at the client. Additionally, the trusted certificate or trust chain of the server certificate must be determined.

    The following shows the TLS configuration (TLS server authentication only): MQ JMS Advanced

  3. The JVM (the IBM MQ JMS client code) needs to know how to handle the TLS cipher suite name string. To allow the correct interpretation you must set a Java parameter for the JVM. For API Gateway these parameters are configured in the file <installpath>/apigateway/system/conf/jvm.xml. You must stop and restart API Gateway for changes to this configuration file to take effect.

    Example change to jvm.xml:

    ...
    <JVMSettings classloader="com.vordel.boot.ServiceClassLoader">
    ...
        <!--
            Parameter is needed for IBM MQ client to correctly interpret TLS
            cipher specification names. See: Axway KB #178678
        -->
        <VMArg name="-Dcom.ibm.mq.cfg.useIBMCipherMappings=false"/>
    
    </JVMSettings>
    </ConfigurationFragment>
    

Tools for analyzing and solving TLS issues

Based on the experience of Axway pre-sales and services consultants, sometimes it can be hard to find out the right configuration options for TLS. You can request details from the MQ server owners or operators, but sometimes it is not practical or takes too long to get those details (especially for testing or in POCs). In those situations it can be helpful to find out what TLS cipher specifications are currently provided by the MQ server and choose a supported one for API Gateway configuration.

This blog post How to list TLS cipher suites a particular web-site offers? provides a Linux bash script that can help to get the necessary information.

The following example shows calling this script:

bash ciphertest.sh localhost:1414 | grep YES

Different vendors or entities name the SSL/TLS cipher suites differently. To get a translation from OpenSSL names to the cipher suite names for Oracle JVM, you can use Testssl.sh - OpenSSL to IANA name mapping.

Improve IBM MQ compatibility

Another idea to improve the compatibility of API Gateway for use with IBM MQ server is to use the extension mechanism provided by API Gateway. You can add third-party Java archives to API Gateway by copying the necessary JAR files to the directory <installdir>/apigateway/ext/lib, which includes them in the classpath of API Gateway. This mechanism is used to add capabilities to the API Gateway. For example, you can add third-party vendor clients or custom developed enhancements to API Gateway this way. See Adding a custom filter for more details.

You can also use this capability to install newer client libraries than the ones that come packaged with API Gateway. As long as the client interfaces have not changed significantly upgrades are possible this way. This is because the libraries in the <installdir>/apigateway/ext/lib subdirectory take precedence over API Gateway out-of-the-box libraries. This enables you to substitute the originally shipped libraries with newer ones.

Install a new IBM MQ client

IBM provides JMS client libraries for IBM MQ named IBM MQ JMS and Java redistributable client. To install a new client library:

  1. Open the IBM MQ client list from IBM: IBM MQ V9 Clients.
  2. Click the link for the required client version in the download table, for example, IBM MQ V9.0.0.9 LTS Clients.
  3. Select the package IBM MQ JMS and Java redistributable client, for example, 9.0.0.9-IBM-MQC-Redist-Java.
  4. Download the fix pack 9.0.0.9-IBM-MQC-Redist-Java.zip.
  5. Unzip the downloaded file and copy the contents of the folder java/lib to <installdir>/apigateway/ext/lib.
  6. Restart API Gateway.

Test TLS connectivity to IBM MQ

Many products are available as prebuilt Docker images from repositories like Docker Hub. You can use an IBM provided Docker image to run an IBM MQ server locally for testing.

Sample commands for using IBM MQ container with TLS for testing

# 1) create self-signed server certificate (key + cert)
$JAVA_HOME/jre/bin/keytool -genkey -keyalg RSA -keysize 2048 -dname "CN=localhost, OU=Axway, O=Testing, L=Frankfurt, ST=Hessen, C=DE" -validity 365 -keypass password -alias mq -keystore mykeystore.jks -storepass password

$JAVA_HOME/jre/bin/keytool -list -v -keystore mykeystore.jks

# 2) export key to p12 container file
$JAVA_HOME/jre/bin/keytool -importkeystore -srckeystore mykeystore.jks -destkeystore mqserver.p12 -deststoretype PKCS12

# 3) convert private key to p8 container without password
openssl pkcs12 -in mqserver.p12 -nocerts -nodes -out mqskey.pem
openssl pkcs8 -in mqskey.pem -topk8 -nocrypt -out mqskey.pk8

# 4) convert self-signed server certificate to PEM
$JAVA_HOME/jre/bin/keytool -exportcert -keystore mykeystore.jks -alias mq -file mqserver.cer
openssl x509 -in mqserver.der -inform DER -out mqscert.pem -outform PEM

# 5) save key and cert to docker volume directory
mkdir -p ~/mqtest/pki/keys/mykey
cp mqskey.pk8 ~/mqtest/pki/keys/mykeytls.key
cp mqscert.pem ~/mqtest/pki/keys/mykey/tls.crt

# 6) start docker container with provided server-cert
docker run \
  --name ibmmq91test \
  --env LICENSE=accept \
  --env MQ_QMGR_NAME=QM1 \
  --env MQ_APP_PASSWORD=passw0rd \
  --label mykey \
  --publish 1414:1414 \
  --publish 9443:9443 \
  --detach \
  --volume qm1data:/mnt/mqm \
  --volume ~/mqtest:/etc/mqm/pki/:rw \
  ibmcom/mq
  
# 7) check if MQ server channel is TLS secured
openssl s_client -showcerts -connect localhost:1414

Conclusion

API Gateway provides out-of-the-box support for IBM MQ server connectivity. If the delivered IBM MQ client version is not suitable for a new IBM MQ server version you can use this how-to guide to configure API Gateway to work with the new IBM MQ version. This is based on the IBM MQ server built-in backward compatibility for older clients. The TLS cipher suites that are available for API Gateway as an MQ client depend on the JVM API Gateway is running with.

Additional Tools for IBM MQ

Another useful tool is IBM MQ Explorer. Although it is intended as an MQ administration tool it is also useful for testing and verification of IBM MQ interaction. More details can be found at IBM Knowledge Center - MQ Explorer.