Tech/Protocols/DHCP

Dynamic Host Configuration Protocol (DHCP)

Open Source Software - Servers

dnsmasq

• License: GPL
• Source Code: https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=summary
• Homepage: https://thekelleys.org.uk/dnsmasq/doc.html
• Manual: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html
• Configuration File: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq.conf.example

ISC DHCP

• EOL: https://www.isc.org/blogs/isc-dhcp-eol/
• Source Code: https://gitlab.isc.org/isc-projects/dhcp

ISC Kea DHCP

• License: MPL2.0 (Some ISC Kea extensions are NOT Open Source)
• Source Code: https://gitlab.isc.org/isc-projects/kea
• Homepage: https://www.isc.org/kea/
• Documentation: https://kea.readthedocs.io/en/latest/arm/config.html

coredhcp-server

• https://github.com/coredhcp/coredhcp

wide

• https://sourceforge.net/projects/wide-dhcpv6/

Open Source Software - Clients

• coredhcp-client
• isc-dhcp-client
• udhcpc
• wide https://sourceforge.net/projects/wide-dhcpv6/

Open Source Software - Tools

• https://www.net.princeton.edu/software/dhcp_probe/

Configuration

Simple DHCP Setup

Assuming a 192.168.100.0 network with a 24 or 255.255.255.0 netmask and gateway at 192.168.100.1

Simple dnsmasq

dnsmasq is easy to configure via the configuration file but I wanted to show that it can be done via CLI first. The -C /dev/null is to cancel out the configuration file for a demo.

docker run -d --cap-add=NET_ADMIN --name=dnsmasqtest debian:stable-slim
docker attach dnsmasqtest
dnsmasq -d -C /dev/null -p 0 -F 192.168.100.2,192.168.100.254 --dhcp-option=3,192.168.100.1 
dnsmasq: started, version 2.89 DNS disabled
dnsmasq: compile time options: IPv6 GNU-getopt DBus no-UBus i18n IDN2 DHCP DHCPv6 no-Lua TFTP conntrack ipset nftset auth cryptohash DNSSEC loop-detect inotify dumpfile
dnsmasq-dhcp: DHCP, IP range 192.168.100.2 -- 192.168.100.254, lease time 1h
exit

With a config file the /etc/dnsmasq.conf might look like:

docker attach dnsmasqtest
cat /etc/dnsmasq.d/test.conf 
port=0
dhcp-range=192.168.100.2,192.168.100.254,12h
dhcp-option=3,1.2.3.4
dhcp-option=option:router,192.168.100.1
dnsmasq -d -C /etc/dnsmasq.d/test.conf 
dnsmasq: started, version 2.89 DNS disabled
dnsmasq: compile time options: IPv6 GNU-getopt DBus no-UBus i18n IDN2 DHCP DHCPv6 no-Lua TFTP conntrack ipset nftset auth cryptohash DNSSEC loop-detect inotify dumpfile
dnsmasq-dhcp: DHCP, IP range 192.168.100.2 -- 192.168.100.254, lease time 12h
exit

Simple Kea

{"Dhcp4": {
    "interfaces-config": {"dhcp-socket-type": "udp"},
    "subnet4": [
        {
            "subnet": "192.168.100.0/24",
            "pools": [ { "pool": "192.168.100.2 - 192.168.100.254" } ],
            "option-data": [{ "name": "routers", "data": "192.0.2.1" }]
        }
    ]
}
}

Resources

• https://thekelleys.org.uk/dnsmasq/docs/dnsmasq.conf.example