1. Introduction — Kea 2.4.0 documentation

# 1. Introduction

Kea is the next generation of DHCP software, developed by Internet Systems Consortium (ISC). It supports both the DHCPv4 and DHCPv6 protocols along with their extensions, e.g. prefix delegation and dynamic updates to DNS.

This guide covers Kea version 2.4.0.

For information about supported platforms see Supported Platforms.

## 1.1. Supported Platforms

In general, this version of Kea builds and runs on any POSIX-compliant system with a C++ compiler (with C++11 support), the Botan cryptographic library, the log4cplus logging library and the Boost system library.

The Kea build has been checked with GCC g++ 4.8.5 and some later versions, and Clang 800.0.38 and some later versions.

ISC regularly tests Kea on many operating systems and architectures, but lacks the resources to test all of them. Consequently, ISC is only able to offer support on a "best-effort" basis for some.

### 1.1.1. Regularly Tested Platforms

Kea is officially supported on Alpine, CentOS, Fedora, RHEL, Ubuntu, Debian, and FreeBSD systems. Kea- 2.4.0 builds have been tested on:

- Alpine — 3.15, 3.16, 3.17

- CentOS — 7

- Debian — 10, 11, 12

- Fedora — 36, 37, 38

- FreeBSD — 12, 13

- RHEL — 8, 9

- Ubuntu — 18.04, 20.04, 22.04

There are currently no plans to port Kea to Windows systems.

### 1.1.2. Best-Effort

The following are platforms on which Kea is known to build and run. ISC makes every effort to fix bugs on these platforms, but may be unable to do so quickly due to lack of hardware, less familiarity on the part of engineering staff, and other constraints.

- macOS — 11, 12, 13

### 1.1.3. Community-Maintained

These systems have once been regularly tested, but official support for it has been abandoned, usually due to discontinued support on their own part. Older versions may not have the required dependencies for building Kea easily available, although it is possible in many cases to compile on those directly from source. The community and interested parties may wish to help with maintenance, and we welcome patch contributions, although we cannot guarantee that we will accept them. All contributions are assessed against the risk of adverse effect on officially supported platforms.

These include platforms past their respective EOL dates, such as:

- Alpine — 3.10, 3.11, 3.12, 3.13, 3.14 (EOL 01 May 2023)

- CentOS — 6, 8 (EOL 31 December 2021)

- Debian — 8, 9 (EOL 30 June 2022)

- Fedora — 31, 32, 33, 34, 35 (EOL 13 December 2022)

- FreeBSD — 10, 11 (EOL 30 September 2021)

- macOS — 10.13, 10.14, 10.15 (EOL 12 September 2022)

- Ubuntu — 14.04, 18.10, 19.04, 19.10, 21.04 (EOL 20 January 2022)

### 1.1.4. Unsupported Platforms

These are platforms on which versions of Kea since 1.7 are known not to build or run:

- Windows (all versions)

- Windows Server (all versions)

- Any platform with OpenSSL 1.0.1 or earlier, which does not also have Botan as an alternative

- Any platform with log4cplus version 1.0.2 or earlier.

## 1.2. Required Software at Runtime

Kea uses various extra software packages which may not be provided in the default installation of some operating systems, nor in the standard package collections. This required software may need to be installed separately. (For the build requirements, also see Build Requirements.)

- Kea supports two cryptographic libraries: Botan and OpenSSL. Only one of them is required to be installed during compilation. Kea uses the Botan library for C++ (https://botan.randombit.net/), version 2.0 or later; support for Botan versions earlier than 2.0 was removed as of Kea 1.7.0. As an alternative to Botan, Kea can use the OpenSSL cryptographic library (https://www.openssl.org/), version 1.0.2 or later.

- Kea uses the log4cplus C++ logging library (https://sourceforge.net/p/log4cplus/wiki/Home/). It requires log4cplus version 1.0.3 or later.

- Kea requires the Boost system library (https://www.boost.org/). Building with the header-only version of Boost is no longer recommended.

Some optional features of Kea have additional dependencies.

- To store lease information in a MySQL database, Kea requires MySQL headers and libraries. This is an optional dependency; Kea can be built without MySQL support.

- To store lease information in a PostgreSQL database, Kea requires PostgreSQL headers and libraries. This is an optional dependency; Kea can be built without PostgreSQL support.

- Integration with RADIUS is provided in Kea via the hook library available to ISC's paid support customers. Use of this library requires the FreeRADIUS-client library to be present on the system where Kea is running. This is an optional dependency; Kea can be built without RADIUS support.

- Kea provides a NETCONF interface with the `kea-netconf` agent. This Kea module requires Sysrepo software when used. Building Kea with NETCONF support requires many dependencies to be installed, which are described in more detail in Installing NETCONF. This is an optional dependency; Kea can be built without NETCONF support.

- To sign and verify DNS updates the Kea DDNS server may use GSS-TSIG, which requires MIT Kerberos 5 or Heimdal libraries. The dependencies required to be installed are described in more detail in GSS-TSIG Compilation. This is an optional dependency; Kea can be built without GSS-TSIG support.

## 1.3. Kea Software

Kea is a modular DHCP server solution. This modularity is accomplished using multiple cooperating processes which, together, provide the server functionality. The following software is included with Kea:

- `keactrl` — This tool starts, stops, reconfigures, and reports the status of the Kea servers.

- `kea-dhcp4` — The DHCPv4 server process. This process responds to DHCPv4 queries from clients.

- `kea-dhcp6` — The DHCPv6 server process. This process responds to DHCPv6 queries from clients.

- `kea-dhcp-ddns` — The DHCP Dynamic DNS process. This process acts as an intermediary between the DHCP servers and external DNS servers. It receives name update requests from the DHCP servers and sends DNS update messages to the DNS servers.

- `kea-admin` — This is a useful tool for database backend maintenance (creating a new database, checking versions, upgrading, etc.).

- `kea-lfc` — This process removes redundant information from the files used to provide persistent storage for the memfile database backend. While it can be run standalone, it is normally run as and when required by the Kea DHCP servers.

- `kea-ctrl-agent` — The Kea Control Agent (CA) is a daemon that exposes a RESTful control interface for managing Kea servers.

- `kea-netconf` - kea-netconf is an agent that provides a YANG/NETCONF interface for configuring Kea.

- `kea-shell` — This simple text client uses the REST interface to connect to the Kea Control Agent.

- `perfdhcp` — This is a DHCP benchmarking tool which simulates multiple clients to test both DHCPv4 and DHCPv6 server performance.

The tools and modules are covered in full detail in this guide. In addition, manual pages are also provided in the default installation.

Kea also provides C++ libraries and programmer interfaces for DHCP. These include detailed developer documentation and code examples.