Installing a cluster on OpenStack in a restricted network

In OKD 4.7, you can install a cluster on Red Hat OpenStack Platform (RHOSP) in a restricted network by creating an internal mirror of the installation release content.

Prerequisites

• Create a registry on your mirror host and obtain the imageContentSources data for your version of OKD.

  Because the installation media is on the mirror host, you can use that computer to complete all installation steps.

• Review details about the OKD installation and update processes.

  • Verify that OKD 4.7 is compatible with your RHOSP version by using the “Supported platforms for OpenShift clusters” section. You can also compare platform support across different versions by viewing the OKD on RHOSP support matrix.

• Verify that your network configuration does not rely on a provider network. Provider networks are not supported.

• Have the metadata service enabled in RHOSP.

About installations in restricted networks

In OKD 4.7, you can perform an installation that does not require an active connection to the Internet to obtain software components. Restricted network installations can be completed using installer-provisioned infrastructure or user-provisioned infrastructure, depending on the cloud platform to which you are installing the cluster.

If you choose to perform a restricted network installation on a cloud platform, you still require access to its cloud APIs. Some cloud functions, like Amazon Web Service’s IAM service, require Internet access, so you might still require Internet access. Depending on your network, you might require less Internet access for an installation on bare metal hardware or on VMware vSphere.

To complete a restricted network installation, you must create a registry that mirrors the contents of the OKD registry and contains the installation media. You can create this registry on a mirror host, which can access both the Internet and your closed network, or by using other methods that meet your restrictions.

Additional limits

Clusters in restricted networks have the following additional limitations and restrictions:

• The ClusterVersion status includes an Unable to retrieve available updates error.

• By default, you cannot use the contents of the Developer Catalog because you cannot access the required image stream tags.

Resource guidelines for installing OKD on RHOSP

To support an OKD installation, your Red Hat OpenStack Platform (RHOSP) quota must meet the following requirements:

A cluster might function with fewer than recommended resources, but its performance is not guaranteed.

An OKD deployment comprises control plane machines, compute machines, and a bootstrap machine.

Control plane and compute machines

By default, the OKD installation process stands up three control plane and three compute machines.

Each machine requires:

• An instance from the RHOSP quota

• A port from the RHOSP quota

• A flavor with at least 16 GB memory, 4 vCPUs, and 25 GB storage space

Bootstrap machine

During installation, a bootstrap machine is temporarily provisioned to stand up the control plane. After the production control plane is ready, the bootstrap machine is deprovisioned.

The bootstrap machine requires:

• An instance from the RHOSP quota

• A port from the RHOSP quota

• A flavor with at least 16 GB memory, 4 vCPUs, and 25 GB storage space

Enabling Swift on RHOSP

Swift is operated by a user account with the swiftoperator role. Add the role to an account before you run the installation program.

Prerequisites

• You have a RHOSP administrator account on the target environment.

• The Swift service is installed.

• On Ceph RGW, the account in url option is enabled.

Procedure

To enable Swift on RHOSP:

1. As an administrator in the RHOSP CLI, add the swiftoperator role to the account that will access Swift:

   $ openstack role add --user <user> --project <project> swiftoperator

Your RHOSP deployment can now use Swift for the image registry.

Defining parameters for the installation program

The OKD installation program relies on a file that is called clouds.yaml. The file describes Red Hat OpenStack Platform (RHOSP) configuration parameters, including the project name, log in information, and authorization service URLs.

Procedure

1. Create the clouds.yaml file:

   • If your RHOSP distribution includes the Horizon web UI, generate a clouds.yaml file in it.

     Remember to add a password to the auth field. You can also keep secrets in a separate file from clouds.yaml.

   • If your RHOSP distribution does not include the Horizon web UI, or you do not want to use Horizon, create the file yourself. For detailed information about clouds.yaml, see Config files in the RHOSP documentation.

     clouds:
       shiftstack:
         auth:
           auth_url: http://10.10.14.42:5000/v3
           project_name: shiftstack
           username: shiftstack_user
           password: XXX
           user_domain_name: Default
           project_domain_name: Default
       dev-env:
         region_name: RegionOne
         auth:
           username: 'devuser'
           password: XXX
           project_name: 'devonly'
           auth_url: 'https://10.10.14.22:5001/v2.0'

2. If your RHOSP installation uses self-signed certificate authority (CA) certificates for endpoint authentication:

   1. Copy the certificate authority file to your machine.

   2. Add the cacerts key to the clouds.yaml file. The value must be an absolute, non-root-accessible path to the CA certificate:

      clouds:
        shiftstack:
          ...
          cacert: "/etc/pki/ca-trust/source/anchors/ca.crt.pem"

      After you run the installer with a custom CA certificate, you can update the certificate by editing the value of the ca-cert.pem key in the cloud-provider-config keymap. On a command line, run: $ oc edit configmap -n openshift-config cloud-provider-config

3. Place the clouds.yaml file in one of the following locations:

   1. The value of the OS_CLIENT_CONFIG_FILE environment variable

   2. The current directory

   3. A Unix-specific user configuration directory, for example ~/.config/openstack/clouds.yaml

   4. A Unix-specific site configuration directory, for example /etc/openstack/clouds.yaml

      The installation program searches for clouds.yaml in that order.

Creating the FCOS image for restricted network installations

Download the Fedora CoreOS (FCOS) image to install OKD on a restricted network Red Hat OpenStack Platform (RHOSP) environment.

Prerequisites

• Obtain the OKD installation program. For a restricted network installation, the program is on your mirror registry host.

Procedure

1. Log in to the Red Hat Customer Portal’s Product Downloads page.

2. Under Version, select the most recent release of OKD 4.7 for RHEL 8.

   The FCOS images might not change with every release of OKD. You must download images with the highest version that is less than or equal to the OKD version that you install. Use the image versions that match your OKD version if they are available.

3. Download the Fedora CoreOS (FCOS) - OpenStack Image (QCOW) image.

4. Decompress the image.

   You must decompress the image before the cluster can use it. The name of the downloaded file might not contain a compression extension, like .gz or .tgz. To find out if or how the file is compressed, in a command line, enter: $ file <name_of_downloaded_file>

5. Upload the image that you decompressed to a location that is accessible from the bastion server, like Glance. For example:

   $ openstack image create --file rhcos-44.81.202003110027-0-openstack.x86_64.qcow2 --disk-format qcow2 rhcos-${RHCOS_VERSION}

   Depending on your RHOSP environment, you might be able to upload the image in either .raw or .qcow2 formats. If you use Ceph, you must use the .raw format.

   If the installation program finds multiple images with the same name, it chooses one of them at random. To avoid this behavior, create unique names for resources in RHOSP.

The image is now available for a restricted installation. Note the image name or location for use in OKD deployment.

Creating the installation configuration file

You can customize the OKD cluster you install on Red Hat OpenStack Platform (RHOSP).

Prerequisites

• Obtain the OKD installation program and the pull secret for your cluster. For a restricted network installation, these files are on your mirror host.

• Have the imageContentSources values that were generated during mirror registry creation.

• Obtain the contents of the certificate for your mirror registry.

• Retrieve a Fedora CoreOS (FCOS) image and upload it to an accessible location.

• Obtain service principal permissions at the subscription level.

Procedure

1. Create the install-config.yaml file.

   1. Change to the directory that contains the installation program and run the following command:

      $ ./openshift-install create install-config --dir=<installation_directory> (1)

      1	For <installation_directory>, specify the directory name to store the files that the installation program creates.

      Specify an empty directory. Some installation assets, like bootstrap X.509 certificates have short expiration intervals, so you must not reuse an installation directory. If you want to reuse individual files from another cluster installation, you can copy them into your directory. However, the file names for the installation assets might change between releases. Use caution when copying installation files from an earlier OKD version.

   2. At the prompts, provide the configuration details for your cloud:

      1. Optional: Select an SSH key to use to access your cluster machines.

         For production OKD clusters on which you want to perform installation debugging or disaster recovery, specify an SSH key that your ssh-agent process uses.

      2. Select openstack as the platform to target.

      3. Specify the Red Hat OpenStack Platform (RHOSP) external network name to use for installing the cluster.

      4. Specify the floating IP address to use for external access to the OpenShift API.

      5. Specify a RHOSP flavor with at least 16 GB RAM to use for control plane and compute nodes.

      6. Select the base domain to deploy the cluster to. All DNS records will be sub-domains of this base and will also include the cluster name.

      7. Enter a name for your cluster. The name must be 14 or fewer characters long.

      8. Paste the pull secret that you obtained from the Pull Secret page on the Red Hat OpenShift Cluster Manager site. This field is optional.

1. In the install-config.yaml file, set the value of platform.openstack.clusterOSImage to the image location or name. For example:

   platform:
     openstack:
         clusterOSImage: http://mirror.example.com/images/rhcos-43.81.201912131630.0-openstack.x86_64.qcow2.gz?sha256=ffebbd68e8a1f2a245ca19522c16c86f67f9ac8e4e0c1f0a812b068b16f7265d

2. Edit the install-config.yaml file to provide the additional information that is required for an installation in a restricted network.

   1. Update the pullSecret value to contain the authentication information for your registry:

      pullSecret: '{"auths":{"<mirror_host_name>:5000": {"auth": "<credentials>","email": "you@example.com"}}}'

      For <mirror_host_name>, specify the registry domain name that you specified in the certificate for your mirror registry, and for <credentials>, specify the base64-encoded user name and password for your mirror registry.

   2. Add the additionalTrustBundle parameter and value.

      additionalTrustBundle: |
        -----BEGIN CERTIFICATE-----
        ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
        -----END CERTIFICATE-----

      The value must be the contents of the certificate file that you used for your mirror registry, which can be an existing, trusted certificate authority or the self-signed certificate that you generated for the mirror registry.

   3. Add the image content resources, which look like this excerpt:

      imageContentSources:
      - mirrors:
        - <mirror_host_name>:5000/<repo_name>/release
        source: quay.example.com/openshift-release-dev/ocp-release
      - mirrors:
        - <mirror_host_name>:5000/<repo_name>/release
        source: registry.example.com/ocp/release

      To complete these values, use the imageContentSources that you recorded during mirror registry creation.

3. Make any other modifications to the install-config.yaml file that you require. You can find more information about the available parameters in the Installation configuration parameters section.

4. Back up the install-config.yaml file so that you can use it to install multiple clusters.

   The install-config.yaml file is consumed during the installation process. If you want to reuse the file, you must back it up now.

Configuring the cluster-wide proxy during installation

Production environments can deny direct access to the Internet and instead have an HTTP or HTTPS proxy available. You can configure a new OKD cluster to use a proxy by configuring the proxy settings in the install-config.yaml file.

Prerequisites

• You have an existing install-config.yaml file.

• You reviewed the sites that your cluster requires access to and determined whether any of them need to bypass the proxy. By default, all cluster egress traffic is proxied, including calls to hosting cloud provider APIs. You added sites to the Proxy object’s spec.noProxy field to bypass the proxy if necessary.

  The Proxy object status.noProxy field is populated with the values of the networking.machineNetwork[].cidr, networking.clusterNetwork[].cidr, and networking.serviceNetwork[] fields from your installation configuration. For installations on Amazon Web Services (AWS), Google Cloud Platform (GCP), Microsoft Azure, and Red Hat OpenStack Platform (RHOSP), the Proxy object status.noProxy field is also populated with the instance metadata endpoint (169.254.169.254).

• If your cluster is on AWS, you added the ec2.<region>.amazonaws.com, elasticloadbalancing.<region>.amazonaws.com, and s3.<region>.amazonaws.com endpoints to your VPC endpoint. These endpoints are required to complete requests from the nodes to the AWS EC2 API. Because the proxy works on the container level, not the node level, you must route these requests to the AWS EC2 API through the AWS private network. Adding the public IP address of the EC2 API to your allowlist in your proxy server is not sufficient.

Procedure

1. Edit your install-config.yaml file and add the proxy settings. For example:

   apiVersion: v1
   baseDomain: my.domain.com
   proxy:
     httpProxy: http://<username>:<pswd>@<ip>:<port> (1)
     httpsProxy: https://<username>:<pswd>@<ip>:<port> (2)
     noProxy: example.com (3)
   additionalTrustBundle: | (4)
       -----BEGIN CERTIFICATE-----
       <MY_TRUSTED_CA_CERT>
       -----END CERTIFICATE-----
   ...

   1	A proxy URL to use for creating HTTP connections outside the cluster. The URL scheme must be http. If you use an MITM transparent proxy network that does not require additional proxy configuration but requires additional CAs, you must not specify an httpProxy value.
   2	A proxy URL to use for creating HTTPS connections outside the cluster. If you use an MITM transparent proxy network that does not require additional proxy configuration but requires additional CAs, you must not specify an httpsProxy value.
   3	A comma-separated list of destination domain names, domains, IP addresses, or other network CIDRs to exclude proxying. Preface a domain with . to match subdomains only. For example, .y.com matches x.y.com, but not y.com. Use * to bypass proxy for all destinations.
   4	If provided, the installation program generates a config map that is named user-ca-bundle in the openshift-config namespace that contains one or more additional CA certificates that are required for proxying HTTPS connections. The Cluster Network Operator then creates a trusted-ca-bundle config map that merges these contents with the Fedora CoreOS (FCOS) trust bundle, and this config map is referenced in the Proxy object’s trustedCA field. The additionalTrustBundle field is required unless the proxy’s identity certificate is signed by an authority from the FCOS trust bundle. If you use an MITM transparent proxy network that does not require additional proxy configuration but requires additional CAs, you must provide the MITM CA certificate.

   The installation program does not support the proxy readinessEndpoints field.

2. Save the file and reference it when installing OKD.

The installation program creates a cluster-wide proxy that is named cluster that uses the proxy settings in the provided install-config.yaml file. If no proxy settings are provided, a cluster Proxy object is still created, but it will have a nil spec.

Installation configuration parameters

Before you deploy an OKD cluster, you provide parameter values to describe your account on the cloud platform that hosts your cluster and optionally customize your cluster’s platform. When you create the install-config.yaml installation configuration file, you provide values for the required parameters through the command line. If you customize your cluster, you can modify the install-config.yaml file to provide more details about the platform.

Required configuration parameters

Required installation configuration parameters are described in the following table:

Network configuration parameters

You can customize your installation configuration based on the requirements of your existing network infrastructure. For example, you can expand the IP address block for the cluster network or provide different IP address blocks than the defaults.

Only IPv4 addresses are supported.

networking:
  clusterNetwork:
  - cidr: 10.128.0.0/14
    hostPrefix: 23

networking:
  serviceNetwork:
   - 172.30.0.0/16

networking:
  machineNetwork:
  - cidr: 10.0.0.0/16

Optional configuration parameters

Optional installation configuration parameters are described in the following table:

sshKey:
  <key1>
  <key2>
  <key3>

Additional Red Hat OpenStack Platform (RHOSP) configuration parameters

Additional RHOSP configuration parameters are described in the following table:

Optional RHOSP configuration parameters

Optional RHOSP configuration parameters are described in the following table:

{
   “type”: “ml.large”,
   “rootVolume”: {
      “size”: 30,
      “type”: “performance”
   }
}

Sample customized install-config.yaml file for restricted OpenStack installations

This sample install-config.yaml demonstrates all of the possible Red Hat OpenStack Platform (RHOSP) customization options.

apiVersion: v1
baseDomain: example.com
controlPlane:
  name: master
  platform: {}
  replicas: 3
compute:
- name: worker
  platform:
    openstack:
      type: ml.large
  replicas: 3
metadata:
  name: example
networking:
  clusterNetwork:
  - cidr: 10.128.0.0/14
    hostPrefix: 23
  machineCIDR: 10.0.0.0/16
  serviceNetwork:
  - 172.30.0.0/16
  networkType: OVNKubernetes
platform:
  openstack:
    region: region1
    cloud: mycloud
    externalNetwork: external
    computeFlavor: m1.xlarge
    apiFloatingIP: 128.0.0.1
pullSecret: '{"auths": ...}'
sshKey: ssh-ed25519 AAAA...
additionalTrustBundle: |
  -----BEGIN CERTIFICATE-----
  ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
  -----END CERTIFICATE-----
imageContentSources:
- mirrors:
  - <mirror_registry>/<repo_name>/release
  source: quay.io/openshift-release-dev/ocp-release
- mirrors:
  - <mirror_registry>/<repo_name>/release
  source: quay.io/openshift-release-dev/ocp-v4.0-art-dev

Generating an SSH private key and adding it to the agent

If you want to perform installation debugging or disaster recovery on your cluster, you must provide an SSH key to both your ssh-agent and the installation program. You can use this key to access the bootstrap machine in a public cluster to troubleshoot installation issues.

You can use this key to SSH into the master nodes as the user core. When you deploy the cluster, the key is added to the core user’s ~/.ssh/authorized_keys list.

Procedure

1. If you do not have an SSH key that is configured for password-less authentication on your computer, create one. For example, on a computer that uses a Linux operating system, run the following command:

   $ ssh-keygen -t ed25519 -N '' \
       -f <path>/<file_name> (1)

   1	Specify the path and file name, such as ~/.ssh/id_rsa, of the new SSH key. If you have an existing key pair, ensure your public key is in the your ~/.ssh directory.

   Running this command generates an SSH key that does not require a password in the location that you specified.

   If you plan to install an OKD cluster that uses FIPS Validated / Modules in Process cryptographic libraries on the x86_64 architecture, do not create a key that uses the ed25519 algorithm. Instead, create a key that uses the rsa or ecdsa algorithm.

2. Start the ssh-agent process as a background task:

   $ eval "$(ssh-agent -s)"

   Example output

   Agent pid 31874

   If your cluster is in FIPS mode, only use FIPS-compliant algorithms to generate the SSH key. The key must be either RSA or ECDSA.

3. Add your SSH private key to the ssh-agent:

   $ ssh-add <path>/<file_name> (1)

   Example output

   Identity added: /home/<you>/<path>/<file_name> (<computer_name>)

   1	Specify the path and file name for your SSH private key, such as ~/.ssh/id_rsa

Next steps

• When you install OKD, provide the SSH public key to the installation program.

Enabling access to the environment

At deployment, all OKD machines are created in a Red Hat OpenStack Platform (RHOSP)-tenant network. Therefore, they are not accessible directly in most RHOSP deployments.

You can configure OKD API and application access by using floating IP addresses (FIPs) during installation. You can also complete an installation without configuring FIPs, but the installer will not configure a way to reach the API or applications externally.

Enabling access with floating IP addresses

Create floating IP (FIP) addresses for external access to the OKD API and cluster applications.

Procedure

1. Using the Red Hat OpenStack Platform (RHOSP) CLI, create the API FIP:

   $ openstack floating ip create --description "API <cluster_name>.<base_domain>" <external_network>

2. Using the Red Hat OpenStack Platform (RHOSP) CLI, create the apps, or Ingress, FIP:

   $ openstack floating ip create --description "Ingress <cluster_name>.<base_domain>" <external_network>

3. Add records that follow these patterns to your DNS server for the API and Ingress FIPs:

   api.<cluster_name>.<base_domain>.  IN  A  <API_FIP>
   *.apps.<cluster_name>.<base_domain>. IN  A <apps_FIP>

   If you do not control the DNS server, you can add the record to your /etc/hosts file. This action makes the API accessible to only you, which is not suitable for production deployment but does allow installation for development and testing.

4. Add the FIPs to the install-config.yaml file as the values of the following parameters:

   • platform.openstack.ingressFloatingIP

   • platform.openstack.apiFloatingIP

If you use these values, you must also enter an external network as the value of the platform.openstack.externalNetwork parameter in the install-config.yaml file.

Completing installation without floating IP addresses

You can install OKD on Red Hat OpenStack Platform (RHOSP) without providing floating IP addresses.

In the install-config.yaml file, do not define the following parameters:

• platform.openstack.ingressFloatingIP

• platform.openstack.apiFloatingIP

If you cannot provide an external network, you can also leave platform.openstack.externalNetwork blank. If you do not provide a value for platform.openstack.externalNetwork, a router is not created for you, and, without additional action, the installer will fail to retrieve an image from Glance. You must configure external connectivity on your own.

If you run the installer from a system that cannot reach the cluster API due to a lack of floating IP addresses or name resolution, installation fails. To prevent installation failure in these cases, you can use a proxy network or run the installer from a system that is on the same network as your machines.

api.<cluster_name>.<base_domain>.  IN  A  <api_port_IP>
*.apps.<cluster_name>.<base_domain>. IN  A <ingress_port_IP>

Deploying the cluster

You can install OKD on a compatible cloud platform.

Prerequisites

• Configure an account with the cloud platform that hosts your cluster.

• Obtain the OKD installation program and the pull secret for your cluster.

Procedure

1. Change to the directory that contains the installation program and initialize the cluster deployment:

   $ ./openshift-install create cluster --dir=<installation_directory> \ (1)
       --log-level=info (2)

   1	For <installation_directory>, specify the
   2	To view different installation details, specify warn, debug, or error instead of info.

   If the cloud provider account that you configured on your host does not have sufficient permissions to deploy the cluster, the installation process stops, and the missing permissions are displayed.

   When the cluster deployment completes, directions for accessing your cluster, including a link to its web console and credentials for the kubeadmin user, display in your terminal.

   Example output

   ...
   INFO Install complete!
   INFO To access the cluster as the system:admin user when using 'oc', run 'export KUBECONFIG=/home/myuser/install_dir/auth/kubeconfig'
   INFO Access the OpenShift web-console here: https://console-openshift-console.apps.mycluster.example.com
   INFO Login to the console with user: "kubeadmin", and password: "4vYBz-Ee6gm-ymBZj-Wt5AL"
   INFO Time elapsed: 36m22s

   The cluster access and credential information also outputs to <installation_directory>/.openshift_install.log when an installation succeeds.

   The Ignition config files that the installation program generates contain certificates that expire after 24 hours, which are then renewed at that time. If the cluster is shut down before renewing the certificates and the cluster is later restarted after the 24 hours have elapsed, the cluster automatically recovers the expired certificates. The exception is that you must manually approve the pending node-bootstrapper certificate signing requests (CSRs) to recover kubelet certificates. See the documentation for Recovering from expired control plane certificates for more information.

   You must not delete the installation program or the files that the installation program creates. Both are required to delete the cluster.

Verifying cluster status

You can verify your OKD cluster’s status during or after installation.

Procedure

1. In the cluster environment, export the administrator’s kubeconfig file:

   $ export KUBECONFIG=<installation_directory>/auth/kubeconfig (1)

   1	For <installation_directory>, specify the path to the directory that you stored the installation files in.

   The kubeconfig file contains information about the cluster that is used by the CLI to connect a client to the correct cluster and API server.

2. View the control plane and compute machines created after a deployment:

   $ oc get nodes

3. View your cluster’s version:

   $ oc get clusterversion

4. View your Operators’ status:

   $ oc get clusteroperator

5. View all running pods in the cluster:

   $ oc get pods -A

Logging in to the cluster by using the CLI

You can log in to your cluster as a default system user by exporting the cluster kubeconfig file. The kubeconfig file contains information about the cluster that is used by the CLI to connect a client to the correct cluster and API server. The file is specific to a cluster and is created during OKD installation.

Prerequisites

• You deployed an OKD cluster.

• You installed the oc CLI.

Procedure

1. Export the kubeadmin credentials:

   $ export KUBECONFIG=<installation_directory>/auth/kubeconfig (1)

   1	For <installation_directory>, specify the path to the directory that you stored the installation files in.

2. Verify you can run oc commands successfully using the exported configuration:

   $ oc whoami

   Example output

   system:admin

Additional resources

• See Accessing the web console for more details about accessing and understanding the OKD web console.

Disabling the default OperatorHub sources

Operator catalogs that source content provided by Red Hat and community projects are configured for OperatorHub by default during an OKD installation. In a restricted network environment, you must disable the default catalogs as a cluster administrator.

Procedure

• Disable the sources for the default catalogs by adding disableAllDefaultSources: true to the OperatorHub object:

  $ oc patch OperatorHub cluster --type json \
      -p '[{"op": "add", "path": "/spec/disableAllDefaultSources", "value": true}]'

Additional resources

• See About remote health monitoring for more information about the Telemetry service

Next steps

• Customize your cluster.

• If the mirror registry that you used to install your cluster has a trusted CA, add it to the cluster by configuring additional trust stores.

• If necessary, you can opt out of remote health reporting.

• Configure image streams for the Cluster Samples Operator and the must-gather tool.

• Learn how to use Operator Lifecycle Manager (OLM) on restricted networks.

• If you did not configure RHOSP to accept application traffic over floating IP addresses, configure RHOSP access with floating IP addresses.