# Introduction

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

This guide covers Kea version &keaversion;.

## Supported Platforms

Kea is officially supported on CentOS, Fedora, Ubuntu, Debian, and FreeBSD systems. It is also likely to work on many other platforms. Kea-&keaversion; builds have been tested on:

- CentOS Linux — 7.1804 (aka 7.5)
- Fedora — 28, 29
- Ubuntu — 16.04, 18.04
- Debian GNU/Linux — 7, 8, 9
- FreeBSD — 11.0
- macOS — 10.13, 10.14

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

## Required Software at Run-time

Running 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. You may need to install this required software separately. (For the build requirements, also see .)

- 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++ (`http://botan.randombit.net/`), version 1.9 or later. Note that support for Botan versions earlier than 2.0 will be removed in Kea 1.6.0 and later. As an alternative to Botan, Kea can use the OpenSSL cryptographic library (`http://www.openssl.org/`), version 1.0.2 or later.

- Kea uses the log4cplus C++ logging library (`http://log4cplus.sourceforge.net/`). It requires log4cplus version 1.0.3 or later.

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

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

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

- In order to store lease information in a Cassandra database (CQL), Kea requires Cassandra headers and libraries. This is an optional dependency in that Kea can be built without Cassandra support.

- Integration with RADIUS is provided in Kea via the hooks library available to our 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 in that Kea can be built without RADIUS support.

- As of the 1.5.0 release, Kea provides a NETCONF interface with the kea-netconf agent. This Kea module is built optionally and requires Sysrepo software when used. Building Kea with NETCONF support requires many dependencies to be installed, which are described in more detail in .

## Kea Software

Kea is modular. Part of this modularity is accomplished using multiple cooperating processes which, together, provide the server functionality. The following software is included with Kea:

- `keactrl` — Tool to start, stop, reconfigure, and report status for 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 DNS servers. It receives name update requests from the DHCP servers and sends DNS update messages to the DNS servers.

- `kea-admin` — 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` — 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 the Kea environment.

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

- `perfdhcp` — 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.