create_wifi_napt_router.sh

sudo emacs /etc/network/interfaces

>
auto eth0
iface eth0 inet dhcp

allow-hotplug wlan0
auto wlan0
iface wlan0 inet static
  address 192.168.1.1
  netmask 255.255.255.0
>

sudo apt-get -y install hostapd
cd /etc/hostapd/
sudo cp /usr/share/doc/hostapd/examples/hostapd.conf.gz ./
sudo gzip -d hostapd.conf.gz

> replace config
# default
interface=wlan0
hw_mode=g
channel=2
macaddr_acl=0

# new
auth_algs=1
ignore_broadcast_ssid=0

driver=nl80211
ssid=aaaaaa
wpa=2
wpa_passphrase=12345678
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
>

sudo sed -i -e "s/#DAEMON_CONF=\"\"/DAEMON_CONF=\"\/etc\/hostapd\/hostapd.conf\"/g" /etc/default/hostapd
sudo systemctl enable hostapd.service
sudo systemctl start hostapd.service

sudo apt-get install isc-dhcp-server
sudo emacs /etc/dhcp/dhcpd.conf
>
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;
↓
#option domain-name "example.org";
#option domain-name-servers ns1.example.org, ns2.example.org;

#authoritative;
↓
authoritative;

ping-check true;


subnet 192.168.1.0 netmask 255.255.255.0 {
  range 192.168.1.10 192.168.1.50;
  option broadcast-address 192.168.1.255;
  option routers 192.168.1.1;
  default-lease-time 600;
  max-lease-time 7200;
  option domain-name "local";
  option domain-name-servers 8.8.8.8, 8.8.4.4;
}
>

sudo emacs /etc/default/isc-dhcp-server
>
INTERFACES=""
↓
INTERFACES="wlan0"
>

sudo /etc/init.d/isc-dhcp-server start
sudo sed -i -e "s/^#net.ipv4.ip_forward=1/net.ipv4.ip_forward=1/" /etc/sysctl.conf
sudo bash -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT
sudo bash -c "iptables-save > /etc/iptables.ipv4.nat"
sudo bash -c "cat <<EOS> /etc/network/if-pre-up.d/iptables
> #!/bin/sh
> /sbin/iptables-restore < /etc/iptables.ipv4.nat
> EOS
> "
sudo chmod +x /etc/network/if-pre-up.d/iptables
sudo reboot now