Providing WiFi Internet connection to wired Ethernet on Linux

dnsmasq.conf

interface=eth0
dhcp-range=10.5.0.50,10.5.0.150,12h

start-nat.sh

#!/bin/sh -e

EXT=wlan0
INT=eth0

ifconfig $INT up 10.5.0.2

echo 1 > /proc/sys/net/ipv4/ip_forward

iptables -F INPUT
iptables -F FORWARD
iptables -F OUTPUT
iptables -t nat -A POSTROUTING -o $EXT -j MASQUERADE
iptables -A FORWARD -i $EXT -o $INT -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i $INT -o $EXT -j ACCEPT

/etc/init.d/dnsmasq restart