Docker - DHCP Server

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I propose to create a Docker ISC Kea Image using base Docker Alpine Linux images, with S6 init system. (ISC Kea is a modern replacement for their DHCP.)

ISC also has a project for a simple GUI interface primarily for Kea and basic for Bind9. There is apparently no Alpine package yet for Stork.

ISC-Kea seems to be provided in a number of packages

Package	Descriptiion	Comment
isc-kea-admin	This package provides backend database initialization and migration scripts and a DHCP benchmark tool. If you are not using a database backend, you may not need this.	Not using a database backend at this time
isc-kea-common	Common libraries for the ISC Kea DHCP server. Install this.	Need this.
isc-kea-ctrl-agent	This package provides the REST API service agent for Kea DHCP.	?
isc-kea-dev	Development headers for ISC Kea DHCP server. Install if you plan to create any custom Kea hooks.	Probably do not need.
isc-kea-dhcp4-server	DHCPv4 server.	Need this.
isc-kea-dhcp6-server	DHCPv6 server.	Do not need at this time.
isc-kea-dhcp-ddns-server	DDNS server.	Need this.
isc-kea-doc	Kea documentation. Highly recommended.	On a Docker container?
isc-kea-hook-flex-option	Flexible Options hook.	What is this?
isc-kea-hook-ha	High Availability hook.	What is this?
isc-kea-hook-lease-cmds	Lease Commands hook.	What is this?
isc-kea-hook-mysql-cb	MySQL Configuration Backend.	Dont need this at this time.
isc-kea-hook-pgsql-cb	PostgreSQL Configuration Backend.	Dont need this.
isc-kea-hook-stat-cmds	Statistics Commands hook.	?
isc-kea-http	This package is essential, install it.	It is essential…
isc-kea-perfdhcp	Optional. Includes a DHCP performance testing tool from ISC.	?
isc-kea-shell	Text client for Kea DHCP Control Agent.	?

From IANA Service Name and Transport Protocol Port online Number Registry:

bootps    67   {tcp, udp}       Bootstrap Protocol Server (DHCP)
bootpc    68   {tcp, udp}       Bootstrap Protocol Client (DHCP)

The Kea Control Agent uses port 8000 by default, but that value can be manually defined in its configuration file. (Usually located at /etc/kea/kea-ctrl-agent.conf.) This port needs to be open and accessible on every server that hosts a Kea DHCP service and a Kea Control Agent.

This is a good case where the Docker network type needs to be set to host. The DHCP server needs to be directly on the host to function.

sudo nmap --script broadcast-dhcp-discover will test the DHCP servers on the same network.

Reference

main dhcp4

kea-dhcp4 -t /app/dhcpv4.conf to test the kea-dhcp4 configuration files /app/dhcpv4.conf
kea-dhcp4 -c /app/dhcpv4.conf to start kea dhcp4 using configuration file /app/dhcpv4.conf

To control which dhcp4 config file to run (basic or plus):

ln -s .config/dhcp_basic.conf .config/dhcp.conf to run basic
ln -s .config/dhcp_plus.conf .config/dhcp.conf to run plus
- The -f flag can be used to overwrite an existing link file instead of deleting first.

The plus configuration allows a secondary backup dhcp server to be operated.

kea-ctrl-agent -t /app/kea-ctrl-agent.conf to test the kea-cont-agent configuration file /app/kea-ctrl-agent.conf
kea-ctrl-agent -c /app/kea-ctrl-agent.conf to start the kea-cont-agent configuration file /app/kea-ctrl-agent.conf