DHCP for Raspberry Pi
2 minute reading time
Recently I ran across the use case where I needed a Raspberry Pi to be connected to the Internet via a WiFI connection, while also providing DHCP leases through an Ethernet connection. I couldn’t find a great way to achieve this with
dhcpcd so instead I grabbed a tool that I’m more familiar with
Before we begin, we need to setup a static IP for the Ethernet interface (
eth0). Since the Ethernet interface will not be connected to the Internet, there’s no need to worry about a lot of the usual fields.
interface eth0 fallback nodhcp profile nodhcp static ip_address=192.168.2.1/24
Below is the config for
dnsmasq which lives in
/etc/dnsmasq.conf. It essentially tells it to only serve DHCP leases on the Ethernet connection of the Raspberry Pi. The addresses it’ll lease out according to the config below is between 192.168.0.50-192.168.0.150 and is leased for 12 hours.
# Configuration file for dnsmasq. # # Format is one option per line, legal options are the same # as the long options legal on the command line. See # "/usr/sbin/dnsmasq --help" or "man 8 dnsmasq" for details. # Listen on this specific port instead of the standard DNS port # (53). Setting this to zero completely disables DNS function, # leaving only DHCP and/or TFTP. port=0 # If you want dnsmasq to listen for DHCP and DNS requests only on # specified interfaces (and the loopback) give the name of the # interface (eg eth0) here. # Repeat the line for more than one interface. interface=eth0 # Or you can specify which interface _not_ to listen on #except-interface= # Or which to listen on by address (remember to include 127.0.0.1 if # you use this.) #listen-address= # Uncomment this to enable the integrated DHCP server, you need # to supply the range of addresses available for lease and optionally # a lease time. If you have more than one network, you will need to # repeat this for each network on which you want to supply DHCP # service. dhcp-range=192.168.0.50,192.168.0.150,12h # Enable DHCPv6. Note that the prefix-length does not need to be specified # and defaults to 64 if missing/ #dhcp-range=1234::2, 1234::500, 64, 12h