Red Hat 블로그
Given the recent general availability of Red Hat Enterprise Linux 7.1 - this post is dedicated to reviewing what’s new in the world of IdM.
Table of Contents
- One-Time Password Authentication
- Migrating Existing Environments to AD Trust
- Backup and Restore
- Identity Management CA Certificate Renewal
- Increased Access Control Granularity
- A New Fresh and Responsive Web UI
- Apply Automember Rules to Existing Users or Hosts
- DNS Interface Enhancements
- Keytab Retrieval Management
- Resolve Group Membership of Active Directory Users Prior to Log In
1. One-Time Password Authentication
One of the best ways to increase authentication security is to require two factor authentication (2FA). A very popular option is to use one-time passwords (OTP). While this technique began in the proprietary space, open standards have emerged (e.g. HOTP: RFC 4226, TOTP: RFC 6238) over time. Identity Management in Red Hat Enterprise Linux 7.1 contains the first commercially supported implementation of the standard OTP mechanism over the Kerberos protocol.
In working to include OTP in Red Hat Enterprise Linux we encountered a unique challenge, namely: how might we provide a mechanism to permit gradual migrations from proprietary technologies to their related open standards? Our solution: as nearly every proprietary technology supports the RADIUS authentication protocol, we provide a way to proxy OTP requests to proprietary RADIUS servers; ensuring the option for a gradual migration path.
For technical details on OTP - visit the FreeIPA design page. Click here to return to the Table of Contents.
2. Migrating Existing Environments to AD Trust
When Identity Management Server is configured via a Winsync synchronization with Active Directory, all users are copied to the Identity Management server with generated POSIX attributes (login name, UID number, GID number, shell, etc.). This approach has several downsides as compared to an infrastructure based on Cross-Realm Trusts, and it is commonly discouraged from being used. However, before Red Hat Enterprise Linux 7.1 it was very difficult to migrate to a trust-based configuration, given that synchronized Active Directory users already had POSIX attributes assigned and, for example, used on-system ACLs for file ownership.
With Red Hat Enterprise Linux 7.1 the new ID Views mechanism allows configuring POSIX attributes and SSH keys for AD users. With this feature administrators can both separate POSIX attributes from the user identity in Active Directory and also potentially remove the Winsync-ed identity from the Identity Management Directory Server taking advantage of Active Directory Trust for user authentication. Either user or group POSIX attributes can be defined in an ID View. The following is a detailed list of use cases covered with the ID Views feature:
- Store POSIX attributes and SSH keys for Active Directory users: Define POSIX attributes or SSH keys for AD users and let them be applied when the AD user authenticates to clients running SSSD with ID Views support or via a legacy “compat” LDAP tree. This capability is useful both for migration from Winsync or in a situation when the Linux Administrator would like to manually define POSIX attributes for Active Directory users, but Active Directory policy does not allow it.
- Migration from the Sync to the Trust solution: Utilize the ID Views interface to configure needed POSIX attributes for existing users synchronized with Winsync and move them back to AD. The mechanism follows the simple procedure:
- Select a user/group entry to be migrated
- Create an ID View override specifying previously used UID or other tools
- Backup the migrated user/group
- Delete the original user/group entry
- Migrating from NIS to IdM/AD solution: A NIS based infrastructure that is being migrated to an IdM/AD based solution often still requires for the original POSIX data to remain unchanged on some NIS domains. In some cases company policies may prevent setting the original POSIX data in the AD directly. In situations like these, ID Views may be leveraged to configure the POSIX data in the Identity Management Server directly.
- Different POSIX/SSH data for different environments: ID Views can also be used to set different POSIX data or user SSH public keys for different environments, for example development, testing or production, based on the respective host groups.
For technical details on migrating existing environments to Trust – visit the FreeIPA design page. Click here to return to the Table of Contents.
3. Backup and Restore
Identity Management in Red Hat Enterprise Linux 7.1 contains backup (
ipa-backup) and restore (
ipa-restore) utilities. While a robust Identity Management Replica infrastructure is the key mechanism for infrastructure recovery (dedicated KB article with reasoning), the new backup and restore utilities are targeted on catastrophic hardware or data failures that cannot be recovered from leveraging the replicas.
For technical details on backup and restore – visit the FreeIPA design page, Fedora 19 Test Day page, or review the
ipa-restore man pages. Click here to return to the Table of Contents.
4. Identity Management CA Certificate Renewal
Before Red Hat Enterprise Linux 7.1, Identity Management CA certificate renewal or change was only possible via an overly complicated manual procedure. The good news is that the latest version of Identity Management introduces tools for automating this critical infrastructure operation. The new feature set covers the following use cases:
- Automated CA certificate renewal: When the CA certificate is nearing its expiration time, it will be automatically renewed. The renewed certificate uses the same key pair and subject name as the old certificate. Note that this option is only available for self-signed CA certificates in CA-ful installs.
- Manual CA certificate renewal: Allow the Identity Management Administrator to manually renew the CA certificate or change its chaining (self-signed to signed by external CA, signed by external CA to self-signed, or signed by external CA to signed by other external CA). The renewed certificate will use the same key pair and subject name as the old certificate. This works for any CA certificate in CA-ful installs.
- Manual install of CA certificate: In CA-less installations, CA certificate renewal is completely in charge of a 3rd party CA. . With Identity Management in Red Hat Enterprise Linux 7.1 it is now possible to manually replace the CA certificate if it was rotated in the 3rd party CA.
- IdM CA Install: The CA-less installation can be turned into a deployment with either self-signed IdM CA or chained to an existing external CA.
Note that CA certificates on clients still need to be updated manually by running the
For technical details on CA certificate renewal – visit the FreeIPA design page or review the
ipa-cacert-manage man pages. Click here to return to the Table of Contents.
5. Increased Access Control Granularity
With the release of Red Hat Enterprise Linux 7.1, the internal access control and permission system was overhauled to offer more granular access control. With new Read Permissions, the Administrator may select different read access to different parts of the Identity Management LDAP tree. Instead of one global read ACI, entries in Identity Management (users, groups, policy objects, SUDO, ...) have their own Read Permission that can be tweaked to control visibility of the entries or their attributes. The new
--bindtype option of the Permission API can now also apply permissions not only to selected users or services in the Identity Management server, but also to any authenticated entity or simply to anonymous.
For technical details on the increased access control granularity – visit the main feature design page, the Read Permissions design page, and the Anonymous and All Permissions design page. Click here to return to the Table of Contents.
6. A New Fresh and Responsive Web UI
Also of note, the Identity Management Server Web interface was reworked and is now based on the open-source PatternFly framework providing common UX principles and patterns usable in enterprise open source web applications. By utilizing the new framework, the Web UI now leverages the Bootstrap 3 front end framework offering much better responsiveness, compared to the old version of the Web UI. It allows the Web UI to abandon absolute position layout and become usable on devices with various screen sizes (e.g. tablets and mobile phones).
For technical details on the new Web UI – visit the FreeIPA design page. Click here to return to the Table of Contents.
7. Apply Automember Rules to Existing Users or Hosts
Identity Management supports a UI and command line for configuring automember rules for automated assignment of new users or hosts in respective groups, according to their characteristics (e.g.
departmentNumber). However, the rules were applied only to new entries. The new CLI and Web UI in Red Hat Enterprise Linux 7.1 allows rebuilding the auto-membership for all or selected existing users or hosts and thus allows easy application of newly configured policies.
For technical details on applying automember rules – visit the FreeIPA design page. Click here to return to the Table of Contents.
8. DNS Interface Enhancements
In Red Hat Enterprise Linux 7.1 the IdM DNS interface was improved with several minor enhancements, namely:
- Internationalized domain (IDN) support: DNS zone and record names now support non-ASCII characters. The DNS record names can be entered with standard Unicode encoding which is then transparently encoded to Punycode required for the IDN support. Note that the canonical host or service DNS names are still limited to ASCII until Kerberos protocol accepts IDN.
- Wildcard DNS names: Support for defining the wildcard DNS record (
*) in the DNS zone is included. The wildcard, once defined, can then be used as a default value for unknown DNS queries for a given zone.
- DNS Forward zones: A new DNS zone type was added to better separate forward and master zones and to thus make the Identity Management DNS interface compliant with the forward zone semantics in BIND. For technical details on forward zones – visit the FreeIPA design page.
Click here to return to the Table of Contents.
9. Keytab Retrieval Management
Before Identity Management in Red Hat Enterprise Linux 7.1, when a Kerberos principal's key was created, it was not possible to retrieve it from the KDC. The only option was to generate a new key. However, the approach was sub-optimal when multiple machines (e.g. in a cluster) needed to share the same key for high availability or load balancing purposes. In these cases, distributing the key had to be performed completely through out-of-band / custom channels.
This version of Identity Management as included with Red Hat Enterprise Linux 7.1 adds a mechanism to retrieve an existing key from the KDC (subject to access control) and resolves the secure distribution channel problem. Leaving to the cluster members the problem of retrieving the key when a new one is created or an old one rotated.
For technical details on keytab retrieval management – visit the FreeIPA design page. Click here to return to the Table of Contents.
10. Resolve Group Membership of Active Directory Users Prior to Log In
Last, but not least, before Red Hat Enterprise Linux 7.1, the full list of group memberships for users from trusted domains was only available for authenticated users on client machines. Authentication was needed because the group memberships were extracted from the PAC which is a part of the Kerberos ticket of the user. For un-authenticated users only the primary POSIX group was available.
In Red Hat Enterprise Linux 7.1, the Identity Management servers can resolve the group memberships for users from trusted domains even for un-authenticated users by reading them from the Active Directory Domain Controllers of the trusted domains directly. In Red Hat Enterprise Linux 7.1, this data is available on all updated client systems as well.
For technical details on resolving group memberships for users from trusted domains – visit the FreeIPA design page. Click here to return to the Table of Contents.
As can been seen – Red Hat Enterprise Linux has incorporated numerous updates to Identity Management. If you have questions on any of the new features or functionality – don’t hesitate to reach out using the comments section below – I look forward to hearing from you!