# Kea 1.7.4, January 29th 2020, Release Notes Welcome to Kea 1.7.4, a monthly development release of Kea. This release is the next step towards having fully multi-threaded DHCP servers, which will eventually become available as 1.8.0. This is a development release. Use with caution! Development releases are not recommended for production use. Changes introduced in this version: 1. **Manipulate HA status**. By popular demand we have implemented a mechanism that allows changing the HA state of partners. Three new commands have been implemented: ha-maintenance-start (which puts one of the server in the partner-in-maintenance state and causes this server to take over the entire DHCP traffic directed to the HA service), ha-maintenance-stop (which reverts back to normal operation), and ha-maintenance-notify (which is an internal command used by servers to notify each other about ongoing maintenance). For more details, see a new section `Controlled Shutdown and Maintenance of DHCP servers` in the Kea ARM. (#1024) 2. **Config Backend support for new DDNS parameters**. Kea 1.7.1 added an ability to specify many DDNS parameters on a per-subnet and per-shared network basis. This greatly improved the flexibility of DHCP and DNS interactions. Unfortunately, that capability was not available for the Config Backend. This limitation is now removed and users can store and tweak the DDNS parameters in the MySQL database. (#946) 3. **BOOTP fixed**. An experimental BOOTP support introduced in Kea 1.7.3 had a serious flaw that made it nearly impossible to use. This has been fixed now. ISC has limited access to BOOTP clients, but the software implementation we were able to use is operating correctly. The BOOTP support is still considered experimental. Please share your experience with it if you can. (#1064) 4. **Performance improvements in DDNS processing**. The code implemented in Kea 1.7.1 added more flexibility regarding DDNS parameters. However, that flexibility needed extra evaluations to be conducted and thus decreased performance a bit, even for cases that didn't use DDNS. This change has now been refactored to have much smaller impact. (#981) 5. **Subnet options are not being loaded from the CB for all subnets**. We were able to identify a somewhat tricky bug in the Config Backend processing. If the options were added to the Config Backend in a specific order, some of the subnets would not retrieve the associated options properly. This problem has now been fixed. (#1093) 6. **Multi-threading**. Our work on enabling multi-threading in Kea has made substantial progress this month. We added thread sanitizer support and started building Kea with unit-tests running with thread sanitizer enabled. There are still some outstanding issues, but we expect to fix them soon. Several more libraries have been made thread-safe: libdhcp++, memfile backend, and MySQL host manager got a thread-safe connection pool. (#880, #889, #894, #1073) 7. **Subnet and shared network default values and inheritance**. The code that handles default parameters and parameters inheritance, such as applying global values to subnet level, has been updated slightly. Although unlikely, there is a small possibility this may affect boot-file-name, client-class, interface, match-client-id, authoritative, next-server, reservation-mode, and server-hostname values in Subnet4 and client-class, interface, interface-id, rapid-commit, and reservation-mode in Subnet6. Please report any odd behavior that you notice. (#724) 8. **Improvements in Option 43 processing**. Kea code for handling option 43 and its suboptions has been improved, in particular with regards to suboptions 0 and 255. This fixes a compatibility problem with Cisco Meraki routers, but may also improve interoperability with other devices that use option 43. (#950) 9. **Fix in the --with-gtest option**. The configure script is now able to detect the libgtest.a properly. Thank you to Niclas Rozenvik for reporting the issue and proposing a fix! (#1080) ## Changes to Release Model The Kea project has been in development for several years now, and it has a significant production deployment base with users who are looking for stability, rather than a constant stream of new "bleeding-edge" features. At the same time, we want to continue developing the software, including some new powerful, but difficult-to-implement, features. As a result, we decided to change the release cycle. Starting from 1.6.0, there are two series of releases: stable and development. Stable releases are what you would expect: stable, released infrequently, without new features or significant changes, very well-tested. Those can be identified by the middle version number being even. The current stable release is 1.6.1. If we discover important bugs that require fixing, we may release 1.6.2, but that will be determined on a case-by-case basis. The next major stable version will be 1.8.0, followed by 2.0.0 in the future. Our team continues development of new features. In particular, we're tackling the difficult problem of being able to use all available CPU cores simultaneously. The multi-threading implementation is a complex task and it is unknown how long it will take before the solution is stable and ready for a production environment. At the same time, we continue to receive a stream of requests for small features and bug fixes. We don't want to force users to wait half a year or more for the fixes and features that are already done. Therefore, we have decided to start issuing development releases on a monthly basis. Those are slightly less well-tested and may have features that are not complete. It is possible that one of the next releases will provide a configuration knob to specify the number of threads in multi-threading, but the actual code won't be extended yet to spawn those threads. The development releases can be easily identified by the middle version number being odd: for example, 1.7.4 is a development release. In February 2020 we will release 1.7.5, the next development version. Once 1.8.0 is out, we will continue our development work with 1.9.0, then 1.9.1, and so on. Our goal is to make the development release available on the last Wednesday of each month. There may be exceptions (such as during holidays), but that's the general plan. We encourage users to test the development releases and report back their findings. For more details on the plan, see ISC's Software Support Policy at https://kb.isc.org/v1/docs/aa-00896. ## Kea overview Kea is a DHCP implementation developed by Internet Systems Consortium, Inc. that features fully functional DHCPv4 and DHCPv6 servers, a dynamic DNS update daemon, a Control Agent (CA) that provides a REST API to control the DHCP and DNS update servers, an example shell client to connect to the CA, a daemon that is able to retrieve YANG configuration and updates from Sysrepo, and a DHCP performance-measurement tool. Both DHCP servers fully support server discovery, address assignment, renewal, rebinding, release, decline, information request, DNS updates, client classification, and host reservations. The DHCPv6 server also supports prefix delegation. Lease information is stored in a CSV file by default; it can optionally be stored in a MySQL, PostgreSQL, or Cassandra database instead. Host reservations can be stored in a configuration file, or in a MySQL, PostgreSQL, or Cassandra database. They can also be retrieved from a RADIUS server, although this functionality is somewhat limited. Kea DHCPv4 and DHCPv6 daemons provide support for YANG models, which are stored in a Sysrepo datastore and can be configured via the NETCONF protocol. This text references issue numbers. For more details, visit the Kea GitLab page at https://gitlab.isc.org/isc-projects/kea/issues. ## License This version of Kea is released under the Mozilla Public License, version 2.0. https://www.mozilla.org/en-US/MPL/2.0 The premium and subscriber-only hook libraries are provided in source code form, under the terms of an End User License Agreement (you will get the source code that you can modify freely, but you are not permitted to redistribute it). ## Download Pre-built ISC packages for current versions of the most popular Linux operating systems are available at: https://cloudsmith.io/~isc/repos/ The Kea source and PGP signature for this release may be downloaded from: https://www.isc.org/download The signature was generated with the ISC code signing key which is available at: https://www.isc.org/pgpkey ISC provides detailed documentation, including installation instructions and usage tutorials, in the Kea Administrator Reference Manual. Documentation is included with the installation or via https://kb.isc.org/docs/kea-administrator-reference-manual in HTML, plain text, or PDF formats. ISC maintains a public open source code tree, a wiki, an issue tracking system, milestone planning, and a roadmap at https://gitlab.isc.org//isc-projects/kea. Limitations and known issues with this release can be found at https://gitlab.isc.org/isc-projects/kea/wikis/known-issues-list. We ask users of this software to please let us know how it worked for you and what operating system you tested on. Feel free to share your feedback on the Kea Users mailing list (https://lists.isc.org/mailman/listinfo/kea-users). Also we would like to hear whether the documentation is adequate and accurate. Please open tickets in the Kea GitLab project for bugs, documentation omissions and errors, and enhancement requests. We want to hear from you even if everything worked. ## Support Professional support for Kea is available from ISC. We encourage all professional users to consider this option; Kea development and maintenance are funded with support subscriptions. For more information on ISC's Kea and DHCP software support see https://www.isc.org/support/. Free best-effort support is provided by our user community via a mailing list. Information on all public email lists is available at https://www.isc.org/community/mailing-list. If you have any comments or questions about working with Kea, please share them to the Kea Users List (https://lists.isc.org/mailman/listinfo/kea-users). Bugs and feature requests may be submitted via GitLab at https://gitlab.isc.org/isc-projects/kea/issues. ## Changes The following summarizes changes and important upgrade notes since the previous release (1.7.3). ``` 1714. [build] razvan Bumped up library version numbers for Kea 1.7.4 release. (Gitlab #1101) 1713. [bug]* tmark Code added under #35 to permit scoping of DDNS behavioral parameters was refactored to improve performance. (Gitlab #981) 1712. [bug] tmark Corrected an issue in the MySQL CB hook library which could cause subnet and shared-network options, properly added to the CB database, to be discarded when fetched from the backend. (Gitlab #1093) 1711. [func] razvan Prepared MySqlHostMgr to be used with multi-threading by using a connection pool with thread context. (Gitlab #1073) 1710. [bug] fdupont The code that handles default parameters and parameters inheritance, such as applying global values to subnet level, has been updated slightly. Although unlikely, there is small possibility this may affect boot-file-name, client-class, interface, match-client-id, authoritative, next-server, reservation-mode, and server-hostname values in Subnet4 and client-class, interface, interface-id, rapid-commit, and reservation-mode in Subnet6. (Gitlab #724) 1709. [func] fdupont MySQL Configuration Backend now allows for storing DDNS related configuration in the database. (Gitlab #946) 1708. [doc] tomek Clarified the relationship between comments and user context. (Gitlab #1079) 1707. [func] marcin High Availability hooks library supports controlled maintenance of the servers. The new ha-maintenance-start command puts one of the servers in the partner-in-maintenance state and causes this server to take over the entire DHCP traffic directed to the HA service. The second server in the in-maintenance state can be safely shutdown for the maintenance. This new mechanism solves the problem present in earlier versions of Kea when the administrator had to rely on the failover mechanism to promote one of the servers to handle the DHCP traffic while the other server was down. (Gitlab #1024) 1706. [bug] fdupont Fixed BOOTP hook. It now properly handles BOOTP packets and sends valid responses. (Gitlab #1064) 1705. [bug] fdupont Modified option 43 parsing to interpret sub-option codes 0 and 255 as PAD and END when no sub-option with these codes are defined. This adds control of illegal but common use of these reserved code points in option 43. (Gitlab #950) 1704. [func] fdupont Prepared memfile lease manager to be used with multi-threading. (Gitlab #894) 1703. [bug] niclas rozenvik A fix in the --with-gtest option. It is now able to detect the libgtest.a. Thank you to Niclas Rozenvik for reporting the issue and proposing a fix! (Gitlab #1080) 1702. [func] razvan Update and delete operations on database back-ends use lease old expire value (internal storage) to detect concurrent actions on the same lease. (Gitlab #1040) 1701. [func] razvan Initialize all option definitions at program startup instead of using lazy initialization to make access thread safe and lock-less. (Gitlab #889) 1700. [func] godfryd Enabled checking Kea merge request in GitLab CI by Danger tool (see https://danger.systems/guides/dangerfile.html). (Gitlab #672) ``` Thank you again to everyone who assisted us in making this release possible. We look forward to receiving your feedback.