Captive Portal Using PHP and iptables Firewall on Linux?

I am following a tutorial for building wifi hotspot based solution in ubuntu using php?

first step is to configure network interfaces according to tutorial /etc/network/interfaces file looks alike

file: /etc/network/interfaces auto lo

iface lo inet loopback

auto eth0

iface eth0 inet dhcp

auto eth1

iface eth1 inet static

address 192.168.3.1

network 192.168.3.0

netmask 255.255.255.0

but i found something like this.

....

a# interfaces(5) file used by ifup(8) and ifdown(8)

auto lo

iface lo inet loopback

please help. http://ift.tt/1OCT0jn