# Raspberry pi as AP

Date: 2018-01-03

In this post, I'll backup the process to turn raspberry pi in to smart AP.

The need is to figure wich device is connecting to the AP and manipulate on it.

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In this guid I'll use raspberry pi 3 mainly because I have one in hands&#8230;

## Pre requires

Raspberry pi 3  
Raspbian os

# AP Installation:

start by update and install :

```shell
sudo apt-get update
sudo apt-get install hostapd isc-dhcp-server iptables-persistent
```

edit the dhcpd.conf file :
```shell
sudo vim /etc/dhcp/dhcpd.conf
```
change :
```shell
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;
```    

to :
```shell
#option domain-name "example.org";
#option domain-name-servers ns1.example.org, ns2.example.org;
```

and change :
```shell
# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
#authoritative;
```

to:
```shell
# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
authoritative;
```

Add at the end :
```shell
subnet 192.168.42.0 netmask 255.255.255.0 {
range 192.168.42.10 192.168.42.150;
option broadcast-address 192.168.42.255;
option routers 192.168.42.1;
default-lease-time 600;
max-lease-time 7200;
option domain-name "local";
option domain-name-servers 8.8.8.8, 8.8.4.4;
}
```

After that edit the dhcp-server :

```shell
sudo vim /etc/default/isc-dhcp-server
```

to :

```shell
GNU nano 2.2.6 File: /etc/default/isc-dhcp-server

# Defaults for isc-dhcp-server initscript
# sourced by /etc/init.d/isc-dhcp-server
# installed at /etc/default/isc-dhcp-server by the maintainer scripts

#
# This is a POSIX shell fragment
#

# Path to dhcpd's config file (default: /etc/dhcp/dhcpd.conf).
#DHCPD_CONF=/etc/dhcp/dhcpd.conf

# Path to dhcpd's PID file (default: /var/run/dhcpd.pid).
#DHCPD_PID=/var/run/dhcpd.pid

# Additional options to start dhcpd with.
# Don't use options -cf or -pf here; use DHCPD_CONF/ DHCPD_PID instead
#OPTIONS=""

# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
# Separate multiple interfaces with spaces, e.g. "eth0 eth1".
INTERFACES="wlan0"


## Set up wlan0 for static IP

sudo ifdown wlan0


edit /etc/network/interfaces :

sudo vim /etc/network/interfaces


with :

iface wlan0 inet static
address 192.168.42.1
netmask 255.255.255.0


After allow-hotplug wlan0

sudo ifconfig wlan0 192.168.42.1


## Configure Access Point

sudo vim /etc/hostapd/hostapd.conf


change the ssid and passphrase

interface=wlan0
ssid=Pi_AP
country_code=US
hw_mode=g
channel=6
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=Raspberry
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP
wpa_group_rekey=86400
ieee80211n=1
wme_enabled=1


run :

sudo nano /etc/default/hostapd


change : #DAEMON\_CONF=&#8221;&#8221; to DAEMON\_CONF=&#8221;/etc/hostapd/hostapd.conf&#8221;  
Don't forget to remove the # in front to activate it!

run :

sudo nano /etc/init.d/hostapd


change : DAEMON\_CONF= to DAEMON\_CONF=/etc/hostapd/hostapd.conf

## Configure Network Address Translation

sudo vim /etc/sysctl.conf


Scroll to the bottom and add

net.ipv4.ip_forward=1


Also run

sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"


Run the following commands to create the network translation between the ethernet port eth0 and the wifi port wlan0

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


To make this happen on reboot (so you don't have to type it every time) run

sudo sh -c "iptables-save > /etc/iptables/rules.v4"


## First test!

run :

sudo /usr/sbin/hostapd /etc/hostapd/hostapd.conf


And see a new access point created

## Finishing up!

sudo service hostapd start
sudo service isc-dhcp-server start
sudo update-rc.d hostapd enable
sudo update-rc.d isc-dhcp-server enable


# Making it smart

Edit the oncommit in dhcpd.conf

sudo vim /etc/dhcp/dhcpd.conf 


and add oncommit :

subnet 192.168.42.0 netmask 255.255.255.0 {
range 192.168.42.10 192.168.42.150;
option broadcast-address 192.168.42.255;
option routers 192.168.42.1;
default-lease-time 600;
max-lease-time 7200;
option domain-name "local";
option domain-name-servers 8.8.8.8, 8.8.4.4;
on commit {
set ClientIP = binary-to-ascii(10, 8, ".", leased-address);
set ClientMac = binary-to-ascii(16, 8, ":", substring(hardware, 1, 6));
log(concat("Commit: IP: ", ClientIP, " Mac: ", ClientMac));
execute("/home/pi/connect.sh", ClientMac, ClientIP);
}
}


and edit the connect.sh script :  
* remember that this a is a blocking script so fork it asap.

#!/usr/bin/bash
# $1 is the mac address
# $2 is the ip
function() {
echo "$1"
}

function $1 $2 &
```

### resources :

[adafruit](https://learn.adafruit.com/setting-up-a-raspberry-pi-as-a-wifi-access-point/install-software)

[raspberrypi.org](https://www.raspberrypi.org/forums/viewtopic.php?t=138730)