Raspberry Pi Access Point

For the Raspberry Pi 3, I used this page except for the /etc/network/interface which I did as below.

Of course, first I had to do Basic Raspberry Pi Set-up.

So I wanted to see the state of the USB card and driver

dmesg | grep rtl
[    6.875478] usbcore: registered new interface driver rtl8192cu
lsusb
Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. 
Bus 001 Device 004: ID 0bda:8176 Realtek Semiconductor Corp. RTL8188CUS 802.11n WLAN Adapter

Next was installing hostapd and some utilities

sudo apt-get install hostapd bridge-utils iw iptables-persistent

I wanted to run a wireless router, so followed, well adapted, the instructions at http://qcktech.blogspot.com/2012/08/raspberry-pi-as-router.html and http://learn.adafruit.com/setting-up-a-raspberry-pi-as-a-wifi-access-point/overview and http://secsup.net/index.php/shaded_grey/comments/comcast_consumer_ipv6_configuration_raspberry_pi_as_bridge_base_station/

Edit/create /etc/hostapd/hostapd.conf as follows:

interface=wlan0
driver=nl80211
ssid=rgnet-pi3
hw_mode=g
channel=6
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=arbitrarykeys
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

And hack /etc/default/hostapd to the following (and be sure to remove the #ash)

DAEMON_CONF="/etc/hostapd/hostapd.conf"

Then configure /etc/network/interfaces

auto lo
 iface lo inet loopback

auto eth0
  iface eth0 inet dhcp

auto wlan0
  iface wlan0 inet static
  address 100.64.64.1/24

Running an access point requires a dhcp server

sudo apt-get install isc-dhcp-server

In /etc/dhcp/dhcpd.conf, make it authoritative by uncommenting

#authoritative;

and then hack

default-lease-time 3600;
max-lease-time 7200;
option domain-name "psg.com rg.net";
option domain-name-servers 8.8.8.8, 8.8.4.4;
option ntp-servers 24.16.172.3;

# No service will be given on this subnet, but declaring it helps the
# DHCP server to understand the network topology.

subnet 192.168.2.0 netmask 255.255.255.0 {
  }

subnet 100.64.64.0 netmask 255.255.255.0 {
  range 100.64.64.10 100.64.64.100;
  option broadcast-address 100.64.64.255;
  option routers 100.64.64.1;
  }

Network 192.168.2.0 is the ether over which I am working doing the install.

And then start the dhcpd to test it

sudo service isc-dhcp-server start

Get autostart scripts

sudo ln -s /etc/init.d/networking /etc/rc2.d/S00networking
sudo ln -s /etc/init.d/hostapd /etc/rc2.d/S02hostapd
sudo ln -s /etc/init.d/isc-dhcp-server /etc/rc2.d/S02isc-dhcp-server

That last may already exist from the apt-get install.

To allow forwarding, in /etc/sysctl.conf, uncomment

net.ipv4.ip_forward=1

Set up the NAT in iptables

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

And the IPTABLE entry for the NAT

sudo iptables-save | tee /etc/iptables/rules.v4

The iptables-persistent will see this id loaded on boot.

It would be wise to test with

# sudo iptables -t nat -S
-P PREROUTING ACCEPT
-P INPUT ACCEPT
-P OUTPUT ACCEPT
-P POSTROUTING ACCEPT
-A POSTROUTING -o eth0 -j MASQUERADE
# sudo iptables -S
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-A FORWARD -i eth0 -o wlan0 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -i wlan0 -o eth0 -j ACCEPT

Sad news

# sudo /usr/sbin/hostapd -B -P /var/run/hostapd.pid /etc/hostapd/hostapd.conf 
Configuration file: /etc/hostapd/hostapd.conf
Failed to create interface mon.wlan0: -95 (Operation not supported)
Could not set channel for kernel driver
Interface initialization failed
wlan0: interface state UNINITIALIZED->DISABLED
wlan0: AP-DISABLED 
wlan0: Unable to setup interface.
wlan0: interface state DISABLED->DISABLED
wlan0: AP-DISABLED 
hostapd_free_hapd_data: Interface wlan0 wasn't started
nl80211: deinit ifname=wlan0 disabled_11b_rates=0

This hack helped

cat > /etc/dnsmasq.conf << EOF
interface=wlan0      # Use interface wlan0
listen-address=100.64.64.1 # Explicitly specify the address to listen on
bind-interfaces      # Bind to the interface to make sure we aren't sending things elsewhere
server=8.8.8.8       # Forward DNS requests to Google DNS
domain-needed        # Don't forward short names
bogus-priv           # Never forward addresses in the non-routed address spaces.
dhcp-range=100.64.64.10,100.64.64.99,12h # Assign IP addresses between 100.64.64.10 and100.64.64.99 with a 12 hour lease time
EOF

Set hostapd to auto-start, though I am not sure that this is needed

sudo update-rc.d hostapd enable

2019.04.04

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Raspberry Pi Access Point

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