Authoritative;
Default-lease-time 600;
Max-lease-time 7200;
Subnet 192.168.1.0 netmask 255.255.255.0 {
Option routers 192.168.1.1;
Option subnet-mask 255.255.255.0;
Option domain-name "freewifi";
Option domain-name-servers 192.168.1.1;
Range 192.168.1.2 192.168.1.40;
}

ifconfig at0 up
    ifconfig at0 192.168.1.1 netmask 255.255.255.0
    ifconfig at0 mtu 1400

modprobe iptable_nat
iptables -A FORWARD -i at0 -o eth0 -j ACCEPT
iptables -A FORWARD -i  eth0  -o at0  -j ACCEPT
iptables -A FORWARD -i eth0 -o at0 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i eth0 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i eth1 -s 0/0 -d 0/0 -j ACCEPT
iptables -A INPUT -i lo -s 0/0 -d 0/0 -j ACCEPT
iptables -A INPUT -i at0 -s 0/0 -d 0/0 -j ACCEPT
iptables -t nat -A PREROUTING -p udp -j DNAT --to-destination 192.168.0.1
iptables -P FORWARD ACCEPT
iptables --append FORWARD --in-interface at0 -j ACCEPT
iptables -t nat -A POSTROUTING --out-interface eth0 -j MASQUERADE
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 53 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 53 -j ACCEPT