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Configuring Zowe certificates in UNIX files

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Configuring Zowe certificates in UNIX files

A keystore directory is used by Zowe to hold the certificate that is used for encrypting communication between Zowe clients and the Zowe z/OS servers. This is a USS path, whose default is /global/zowe/keystore. The keystore directory also holds the truststore used to hold public keys of any servers that Zowe trusts. When Zowe is launched, the instance directory configuration file instance.env specifies the location of the keystore directory that Zowe's servers use to locate their TLS certificate and trust store. For more information on Zowe launch, see Creating and configuring the Zowe instance directory.

To create the keystore directory, use the <RUNTIME_DIR>/bin/zowe-setup-certificates.sh script. This takes its input parameters from the file <RUNTIME_DIR>/bin/zowe-setup-certificates.env.

The default directory that the certificates are generated in is /global/zowe/keystore. At many z/OS installations, access to this directory is restricted to privileged users. You must change the value of KEYSTORE_DIRECTORY in zowe-setup-certificates.env to choose a directory that you have write authority for, or else ensure that the execution of the zowe-setup-certificates.sh step is performed by a system programmer with site knowledge of where the certificate should be stored. This will ensure that the public key is readable and that the private key access is controlled.

The Zowe setup can work with the following scenarios:

Self-signed certificate​

Zowe can create its own certificate and sign it with a certificate authority that is also creeated by Zowe. This is sometimes referred to as a self-signed certificate, and is the simplest scenario to do for evaluation and proof of concept deployment of Zowe.

<RUNTIME_DIR>/bin/zowe-setup-certificates.sh

The following video shows how to create a self-signed certificate.

Download the script

If you are using a self-signed certificate, then you will be challenged by your browser when logging in to Zowe to accept working with an untrusted certificate authority. Depending on the browser you are using, you may be able to add an exception and proceed to the web page, or you may be prevented from continuing altogether.

Manually import a certificate authority into a web browser​

To avoid the browser untrusted CA challenge, you can import Zowe's certificates into the browser to avoid untrusted network traffic challenges. For more information, see Import the local CA certificate to your browser.

To avoid requiring each browser to trust the CA that signed the Zowe certificate, you can use a public certificate authority such as Symantec, Comodo, Let's Encrypt, or _GoDaddy_to create a certificate. These certificates are trusted by all browsers and most REST API clients. This option, however, requires a manual process to request a certificate and may incur a cost payable to the publicly trusted CA.

Generate a Keystore Directory​

The file <RUNTIME_DIR>/bin/zowe-setup-certificates.sh takes its input parameters from <RUNTIME_DIR>/bin/zowe-setup-certificates.env, and the KEYSTORE_DIRECTORY parameter specifies the directory that wil be created to store the certificate. The default value is /global/zowe/keystore.

Generate a certificate with custom values​

We recommend that you review all parameters in the zowe-setup-certificates.env file, and customize the values for variables to meet your requirements. One example is to set your preferred location to generate certificates and keystores.

Use the the following procedure to customize the values for variables in the zowe-setup-certificates.env file.

Follow these steps:

  1. Copy the bin/zowe-setup-certificates.env file from the read-only location to a new <your_directory>/zowe-setup-certificates.env location.

  2. Customize the values for the variables based on the descriptions that are provided in the zowe-setup-certificates.env file.

  3. Execute the following command with the customized environment file:

     bin/zowe-setup-certificates.sh –p <your_directory>/zowe-setup-certificates.env [-l <log_directory>]

    where:

    • <your_directory>

      specifies the location of your customized environment file

    • <log-directory>

      is an optional parameter that overrides the default log output directory of /global/zowe/logs, if it is writable, or ~/zowe/logs.

The keystore and certificates are generated based on the customized values in the bin/zowe-setup-certificates.env file.

The zowe-setup-certificates.sh command also generates the zowe-certificates.env file in the KEYSTORE_DIRECTORY directory. This file is used in the Zowe instance configuration step. For more information, see Creating and configuring the Zowe instance directory.

Configure zowe-setup-certificates.env to use existing certificates​

The following procedure shows how to configure the zowe-setup-certificates.env file to use the existing certificates.

Follow these steps:

  1. Update the value of EXTERNAL_CERTIFICATE. The value needs to point to a keystore in PKCS12 format that contains the certificate with its private key. The file needs to be transferred as a binary to the z/OS system.

  2. Update the value of KEYSTORE_PASSWORD. The value is a password to the PKCS12 keystore specified in the EXTERNAL_CERTIFICATE variable.

  3. Update the value of EXTERNAL_CERTIFICATE_ALIAS to the alias of the server certificate in the keystore.

    Note: If you do not know the certificate alias, run the following command where externalCertificate.p12 is a value of EXTERNAL_CERTIFICATE in the zowe-setup-certificates.env file.

    keytool -list -keystore externalCertificate.p12 -storepass password -storetype pkcs12 -v

    Expected output:

    Keystore type: PKCS12
    Keystore provider: SUN
    Your keystore contains 1 entry
    Alias name: apiml
    Creation date: Oct 9, 2019
    Entry type: PrivateKeyEntry
    Certificate chain length: 3
    ...

    In this case, the alias can be found in Alias name: apiml. Therefore, set EXTERNAL_CERTIFICATE_ALIAS=apiml.

  4. Update the value of EXTERNAL_CERTIFICATE_AUTHORITIES to the path of the public certificate of the certificate authority that has signed the certificate. You can add additional certificate authorities separated by spaces.

    Note: Be sure to specify the complete value in quotes. This can be used for certificate authorities that have signed the certificates of the services that you want to access through the API Mediation Layer.

  5. (Optional) If you have trouble getting the certificates and you want only to evaluate Zowe, you can switch off the certificate validation by setting VERIFY_CERTIFICATES=false and NONSTRICT_VERIFY_CERTIFICATES=false. This setting continues to use HTTPS, but the API Mediation Layer will not validate any certificate.

    Important! Switching off certificate evaluation is a non-secure setup. Please talk to your system administrator before you do so and only use these options for troubleshooting purpose.

    The following script is the part of zowe-setup-certificates.env file that uses existing certificates:

    # Should APIML verify certificates of services it uses in strict mode - true/false
    # "strict mode" will verify if the certificates is trusted in truststore, also verify
    # if the certificate Common Name or Subject Alternate Name (SAN) match the service hostname.
    # if this value is true, NONSTRICT_VERIFY_CERTIFICATES will be ignored.
    VERIFY_CERTIFICATES=true
    # Should APIML verify certificates of services it uses in non-strict mode - true/false
    # "non-strict mode" will verify if the certificates is trusted in truststore, but
    # certificate Common Name or Subject Alternate Name (SAN) will NOT be checked.
    NONSTRICT_VERIFY_CERTIFICATES=true
    # optional - Path to a PKCS12 keystore with a server certificate for APIML
    EXTERNAL_CERTIFICATE=/path/to/keystore.p12
    # optional - Alias of the certificate in the keystore
    EXTERNAL_CERTIFICATE_ALIAS=servercert
    # optional - Public certificates of trusted CAs
    EXTERNAL_CERTIFICATE_AUTHORITIES="/path/to/cacert_1.cer /path/to/cacert_2.cer"
    # Select a password that is used to secure EXTERNAL_CERTIFICATE keystore and 
    # that will be also used to secure newly generated keystores for API Mediation
    KEYSTORE_PASSWORD=mypass

You may encounter the following message:

apiml_cm.sh --action trust-zosmf has failed. See $LOG_FILE for more details
ERROR: z/OSMF is not trusted by the API Mediation Layer. Make sure ZOWE_ZOSMF_HOST and ZOWE_ZOSMF_PORT variables define the desired z/OSMF instance.
ZOWE_ZOSMF_HOST=${ZOWE_ZOSMF_HOST}   ZOWE_ZOSMF_PORT=${ZOWE_ZOSMF_PORT}
You can also specify z/OSMF certificate explicitly in the ZOSMF_CERTIFICATE environmental variable in the zowe-setup-certificates.env file.

This error must be resolved before you can proceed with the next installation step.

Note:

On many z/OS systems, the certificate for z/OSMF is not signed by a trusted CA and is a self-signed certificate by the z/OS system programmer who configured z/OSMF. Based on the configuration, there is chance zowe-setup-certificates.sh may not be able to detect z/OSMF certificate and certificate authority successfully. In this case, you can define ZOSMF_CERTIFICATE= manually to let Zowe trust the certificate you determined.

If the certificate is from a recognized CA but for a different host name, which can occur when a trusted certificate is copied from one source and reused within a z/OS installation for different servers other than that it was originally created for. We recommended to regenerate certificates with correct HOSTNAME= option.

Switching off VERIFY_CERTIFICATES, especially NONSTRICT_VERIFY_CERTIFICATES is not recommended. It may expose security risks to your z/OS system.

Hints and tips​

Learn about some hints and tips that you might find useful when you create certificates.

You create the certificates by running the script zowe-setup-certificates.sh. You do not need to rerun the script after the first time you install Zowe, unless instructed otherwise by SMP/E HOLDDATA or the release notes for that release.

The creation of the certificates is controlled by the zowe-setup-certificates.env file, and you should have placed a copy of that file in your instance directory INSTANCE_DIR.

  1. Keystore

    In your copy of the zowe-setup-certificates.env file, specify the location where you want the zowe-setup-certificates.sh script to place the keys it generates.

    KEYSTORE_DIRECTORY=/my/zowe/instance/keystore

    By default, a keystore can be shared by all instances, which is also recommended. The default location is /global/zowe/keystore. You can use a different shared location if you prefer. The Zowe instance uses the keystore that you specify in instance.env in your instance directory INSTANCE_DIR. This can be the shared location or you can create another keystore in a different location for that instance and use that one instead. A single, shared keystore is recommended.

  2. Hostname and IP address

    You specify the hostname and IP address with the following keywords in the zowe-setup-certificates.env file.

    HOSTNAME= 
    IPADDRESS=

    The certificates require the value of HOSTNAME to be an alphabetic hostname. Numeric hostnames such as an IP address are not allowed.

    The zowe-setup-certificates.sh script attempts to discover the IP address and hostname of your system if you leave these unconfigured in zowe-setup-certificates.env.

    On systems with their own internal IP domain, the hostname might not resolve to the external IP address. This happens on ZD&T ADCD-derived systems, where the hostname is usually S0W1.DAL-EBIS.IHOST.COM which resolves to 10.1.1.2. When the script cannot determine the hostname or the external IP address, it will ask you to enter the IP address manually during the dialog. If you have not specified a value for HOSTNAME in zowe-setup-certificates.env, then the script will use the given IP address as the hostname. This will fail because certificates cannot have a numeric hostname.

    Therefore, you must specify an alphabetic hostname such as the following one on ZD&T systems before you run the script zowe-setup-certificates.sh.

    HOSTNAME=S0W1.DAL-EBIS.IHOST.COM

    The values of HOSTNAME and IPADDRESS that the script discovered are appended to the zowe-setup-certificates.env file unless they were already set in that file or as shell environment variables before you ran the script.

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