dhcpcd — a DHCP client

/etc/dhcpcd.conf

interface eth0
static ip_address=
destination routers

interface wlan0
static ip_address=192.168.31.226/24
static routers=192.168.31.1
static domain_name_servers=127.0.0.1

• http://manpages.ubuntu.com/manpages/trusty/man5/dhclient.conf.5.html
• http://manpages.ubuntu.com/manpages/trusty/man8/dhclient.8.html