Chapter 4. Planning your CA services
Identity Management (IdM) in Red Hat Enterprise Linux provides different types of certificate authority (CA) configurations. The following sections describe different scenarios and provide advice to help you determine which configuration is best for your use case.
4.1. CA Services available in an IdM server
You can install an Identity Management (IdM) server with an integrated IdM certificate authority (CA) or without a CA.
Table 4.1. Comparing IdM with integrated CA and without a CA
|Integrated CA||Without a CA|
IdM uses its own public key infrastructure (PKI) service with a CA signing certificate to create and sign the certificates in the IdM domain.
The external CA can be a corporate CA or a third-party CA.
IdM does not set up its own CA, but uses signed host certificates from an external CA.
Installing a server without a CA requires you to request the following certificates from a third-party authority:
If the integrated CA is subordinate to an external CA, the certificates issued within the IdM domain are potentially subject to restrictions set by the external CA for various certificate attributes, such as:
Managing certificates outside of IdM causes a lot of additional activities, such as :
Works best for:
Environments that allow you to create and use your own certificate infrastructure.
Very rare cases when restrictions within the infrastructure do not allow you to install certificate services integrated with the server.
Switching from the self-signed CA to an externally-signed CA, or the other way around, as well as changing which external CA issues the IdM CA certificate, is possible even after the installation. It is also possible to configure an integrated CA even after an installation without a CA.
4.2. CA subject DN
The Certificate Authority (CA) subject distinguished name (DN) is the name of the CA. It must be globally unique in the Identity Management (IdM) CA infrastructure and cannot be changed after the installation. In case you need the IdM CA to be externally signed, you might need to consult the administrator of the external CA about the form your IdM CA Subject DN should take.
4.3. Guidelines for distribution of CA services
Following steps provide guidelines for the distribution of your certificate authority (CA) services.
- Install the CA services on more than one server in the topology
Replicas configured without a CA forward all certificate operations requests to the CA servers in your topology.
If you lose all servers with a CA, you will lose all the CA configuration without any chance of recovery. In such case you need to set up new CA and issue and install new certificates.
- Maintain a sufficient number of CA servers to handle the CA requests in your deployment
For recommendation see the following table:
Table 4.2. Guidelines for setting up appropriate number of CA servers
|Description of the deployment||Suggested number of CA servers|
A deployment with a very large number of certificates issued
Three or four CA servers
A deployment with bandwidth or availability problems between multiple regions
One CA server per region, with a minimum of three servers total for the deployment
All other deployments
Two CA servers