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Manual Chapter: Managing Device Trust
Manual Chapter
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What is device trust?

Before any BIG-IP® devices on a local network can be members of a Sync-Failover device group to synchronize configuration data or fail over to one another, they must establish a trust relationship known as device trust. Device trust between any two BIG-IP devices on the network is based on mutual authentication through the signing and exchange of x509 certificates.

Devices on a local network that trust one another constitute a trust domain. A trust domain is a collection of BIG-IP devices that trust one another.

The trust domain is represented by a system-generated device group named device_trust_group, which the system uses internally to synchronize trust domain information across all devices. You cannot delete this special device group from the system.

Note: You can add devices to a local trust domain from a single device on the network. You can also view the identities of all devices in the local trust domain from a single device in the domain. However, to maintain or change the authority of each trust domain member, you must log in locally to each device.

Types of trust authority

Within a local trust domain, in order to establish device trust, you designate each BIG-IP® device as either a peer authority or a subordinate non-authority.

About certificate signing authorities

A certificate signing authority can sign x509 certificates for another BIG-IP device that is in the local trust domain. For each authority device, you specify another device as a peer authority device that can also sign certificates. In a standard redundant system configuration of two BIG-IP devices, both devices are typically certificate signing authority devices.

Important: For security reasons, F5 Networks recommends you limit the number of authority devices in a local trust domain to as few as possible.

About peer authorities

A peer authority is another device in the local trust domain that can sign certificates if the certificate signing authority is not available. In a standard redundant system configuration of two BIG-IP devices, each device is typically a peer authority for the other.

About subordinate non-authorities

A subordinate non-authority device is a device for which a certificate signing authority device signs its certificate. A subordinate device cannot sign a certificate for another device. Subordinate devices provide an additional level of security because in the case where the security of an authority device in a trust domain is compromised, the risk of compromise is minimized for any subordinate device. Designating devices as subordinate devices is recommended for device groups with a large number of member devices, where the risk of compromise is high.

Device identity

The devices in a BIG-IP® device group use x509 certificates for mutual authentication. Each device in a device group has an x509 certificate installed on it that the device uses to authenticate itself to the other devices in the group.

Device identity is a set of information that uniquely identifies that device in the device group, for the purpose of authentication. Device identity consists of the x509 certificate, plus this information:

  • Device name
  • Host name
  • Platform serial number
  • Platform MAC address
  • Certificate name
  • Subjects
  • Expiration
  • Certificate serial number
  • Signature status
Tip: From the Device Trust: Identity screen in the BIG-IP Configuration utility, you can view the x509 certificate installed on the local device.

Device discovery in a local trust domain

When a BIG-IP® device joins the local trust domain and establishes a trust relationship with peer devices, the device and its peers exchange their device properties and device connectivity information. This exchange of device properties and IP addresses is known as device discovery.

For example, if a device joins a trust domain that already contains three trust domain members, the device exchanges device properties with the three other domain members. The device then has a total of four sets of device properties defined on it: its own device properties, plus the device properties of each peer. In this exchange, the device also learns the relevant device connectivity information for each of the other devices.

Establishing device trust

Before you begin this task, verify that:

  • Each BIG-IP® device that is to be part of the local trust domain has a device certificate installed on it.
  • The local device is designated as a certificate signing authority.

You perform this task to establish trust among devices on one or more network segments. Devices that trust each other constitute the local trust domain. A device must be a member of the local trust domain prior to joining a device group.

By default, the BIG-IP software includes a local trust domain with one member, which is the local device. You can choose any one of the BIG-IP devices slated for a device group and log into that device to add other devices to the local trust domain. For example, devices Bigip_1, Bigip_2, and Bigip_3 each initially shows only itself as a member of the local trust domain. To configure the local trust domain to include all three devices, you can simply log into device Bigip_1 and add devices Bigip_2 and Bigip_3 to the local trust domain; there is no need to repeat this process on devices Bigip_2 and Bigip_3.

  1. On the Main tab, click Device Management > Device Trust > Device Trust Members .
  2. Click Add.
  3. From the Device Type list, select Peer or Subordinate.
  4. Type a device IP address, administrator user name, and administrator password for the remote BIG-IP® device with which you want to establish trust. The IP address you specify depends on the type of BIG-IP device:
    • If the BIG-IP device is an appliance, type the management IP address for the device.
    • If the BIG-IP device is a VIPRION® device that is not licensed and provisioned for vCMP®, type the primary cluster management IP address for the cluster.
    • If the BIG-IP device is a VIPRION device that is licensed and provisioned for vCMP, type the cluster management IP address for the guest.
    • If the BIG-IP device is an Amazon Web Services EC2 device, type one of the Private IP addresses created for this EC2 instance.
  5. Click Retrieve Device Information.
  6. Verify that the certificate of the remote device is correct, and then click Device Certificate Matches.
  7. In the Name field, verify that the name of the remote device is correct.
  8. Click Add Device.
After you perform this task, the local device is now a member of the local trust domain. Also, the BIG-IP system automatically creates a special Sync-Only device group for the purpose of synchronizing trust information among the devices in the local trust domain, on an ongoing basis.
Repeat this task to specify each device that you want to add to the local trust domain.

Adding a device to the local trust domain

Verify that each BIG-IP® device that is to be part of a local trust domain has a device certificate installed on it.
Follow these steps to log in to any BIG-IP® device on the network and add one or more devices to the local system's local trust domain.
Note: Any BIG-IP devices that you intend to add to a device group at a later point must be members of the same local trust domain.
  1. On the Main tab, click Device Management > Device Trust > Device Trust Members .
  2. Click Add.
  3. From the Device Type list, select Peer or Subordinate.
  4. Type a device IP address, administrator user name, and administrator password for the remote BIG-IP® device with which you want to establish trust. The IP address you specify depends on the type of BIG-IP device:
    • If the BIG-IP device is an appliance, type the management IP address for the device.
    • If the BIG-IP device is a VIPRION® device that is not licensed and provisioned for vCMP®, type the primary cluster management IP address for the cluster.
    • If the BIG-IP device is a VIPRION device that is licensed and provisioned for vCMP, type the cluster management IP address for the guest.
    • If the BIG-IP device is an Amazon Web Services EC2 device, type one of the Private IP addresses created for this EC2 instance.
  5. Verify that the certificate of the remote device is correct, and then click Device Certificate Matches.
  6. In the Name field, verify that the name of the remote device is correct.
  7. Click Add Device.
After you perform this task, the local device and the device that you specified in this procedure have a trust relationship and, therefore, are qualified to join a device group.

Troubleshooting tips for establishing trust

This table lists possible problems that might occur when you are attempting to add a BIG-IP® device to a local trust domain. Each problem shows a recommended action.

Problem Recommended action
Another device with the same name already exists in the trust domain. Change the name of the device that you are adding to the trust domain.
The version of BIG-IP software on the device does not match the version of the devices in the trust domain. Make sure that the BIG-IP version on the device you are adding exactly matches the version on the devices in the trust domain, including the hotfix version (if any).
The exact time reported on the device you are adding is out of sync with the time on the other devices in the trust domain. Make sure that you have a Network Time Protocol (NTP) server configured for the device.
There is no config sync address configured on the device. On the device you are adding, configure a config sync IP address. We recommend that you specify the self IP address associated with the device's internal VLAN.

Managing trust authority for a device

You can use a Reset Device Trust wizard in the BIG-IP® Configuration utility to manage the certificate authority of a BIG-IP device in a local trust domain. Specifically, you can:

  • Retain the current authority (for certificate signing authorities only).
  • Regenerate the self-signed certificate for a device.
  • Import a user-defined certificate authority. In this case, a typical scenario is to generate another signing certificate and key through another certificate authority (such as OpenSSL) and then import the certificate to the BIG-IP system. The BIG-IP system then uses the certificate and key to sign the certificate signing request (CSR) that the BIG-IP generates. The resulting certificate is used to establish trust with other devices in the trust domain.
Warning: If you reset trust authority on a certificate signing authority by retaining the authority of the device, you must subsequently recreate the local trust domain and the device group. If you reset trust authority on a subordinate non-authority, the BIG system removes the non-authority device from the local trust domain. You can then re-add the device as an authority or non-authority device.
  1. On the Main tab, click Device Management > Device Trust > Local Domain .
  2. In the Trust Information area of the screen, click Reset Device Trust.
  3. Choose a certificate signing authority option, and then click Update.
    The system prompts you to confirm your choice.
When you confirm your choice, the system changes the Authority Type.

Viewing status for device trust

For any BIG-IP devices that have a trust relationship, the BIG-IP® system automatically puts these devices into a special Sync-Only device group for device trust and syncs the trust information. (BIG-IP devices in this device group can also be members of other device groups that you create.) If any trust issue occurs between devices in the trust device group, this indicates that you need to re-establish trust between two or more devices. In this case, the BIG-IP system displays a config sync status of Changes Pending. You can use the BIG-IP® Configuration utility to view the config sync status of this trust device group, which has a system-supplied device group name.
Note: A device in a trust domain that is not a member of a Sync-Failover device group normally shows a status in the BIG-IP Configuration utility of NOT WATCHED. If you add the device to a Sync-Failover device group, the status shows as either In Sync or Changes Pending.
  1. On the Main tab, click Device Management > Overview .
  2. In the Device Groups area of the screen, click the arrow next to the name of the relevant device group.
    The screen expands to show a summary and details of the sync status of the selected device group, as well as a list of the individual devices within the device group.
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