Raspberry Pi using as access point

Hostapd + dnsmasq for Raspberry Pi 

Last time I used Android phone as a keyboard and mouse to remotely control the RPi X-server, but it required WiFi connection to login the RPi if I need to control the terminal. 
This time I tried to make RPi work as an access point to directly communicate with Android phone.

1. hostapd settingsInstall hostapd package.

   sudo apt-get install bridge-utils hostapd

   Get hostpad that is for the RTL8188CUS chipset which is used for Edimax EW-7811Uh.

   wget http://dl.dropbox.com/u/1663660/hostapd/hostapd.zipunzip hostapd.zip

   Replace the hostapd that is installed with the package.
   

   sudo mv /usr/sbin/hostapd /usr/sbin/hostapd.original
   sudo mv hostapd /usr/sbin/hostapd.edimax
   sudo ln -sf /usr/sbin/hostapd.edimax /usr/sbin/hostapd
   sudo chown root.root /usr/sbin/hostapd
   sudo chmod 755 /usr/sbin/hostapd

   If eth0 and wlan0 need to be bridged, edit the interfaces file.
   

    sudo nano /etc/network/interfaces

   Modify the file as below. (after the part related to wlan0)
   

   auto br0
   iface br0 inet dhcp
   bridge_ports eth0 wlan0

    Create hostapd.conf file
   

   sudo nano /etc/hostapd/hostapd.conf

   Add the following lines.
   

   interface=wlan0
   driver=rtl871xdrv
   bridge=br0
   ssid=[NETWORK NAME]
   channel=6
   wmm_enabled=0
   wpa=1
   wpa_passphrase=[PASSWORD]
   wpa_key_mgmt=WPA-PSK
   wpa_pairwise=TKIP
   rsn_pairwise=CCMP
   auth_algs=1
   macaddr_acl=0

   Run hostapd and see if network is detected by Android phone.
   

   sudo hostapd -dd /etc/hostapd/hostapd.conf

   Modify hostpad file if you want to run hostapd at the startup.
   

   sudo nano /etc/default/hostapd

   Uncomment "DAEMON_CONF" in the file and add the path to the file.
   

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

   Reboot the system and see if hostapd is automatically run.

   sudo shutdown -r now

   
   
   
2. dnsmasq settings
   hostapd is to make it RPi as access point.
   Now, we install dnsmasq to automatically assign the IP address to the clients.
   Install dnsmasq.

   sudo apt-get install dnsmasq

   This will automatically start the dnsmasq, so stop it.
   

   sudo service dnsmasq stop

   Create the new configuration file.

   sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.original

   sudo touch /etc/dnsmasq.conf

   Edit the file as below.

   interface=wlan0

   expand-hosts

   domain=local

   dhcp-range=10.0.0.10,10.0.0.20,24h

   dhcp-option=3,10.0.0.1

    Edit the interfaces file again.

   sudo nano /etc/network/interfaces

   Comment out or delete the part modified previously, then modify it as below. (section1) 
   

   #auto br0
   #iface br0 inet dhcp
   #bridge_ports eth0 wlan0

   iface wlan0 inet static

   address 10.0.0.1

   network 10.0.0.0

   netmask 255.255.255.0

   broadcast 10.0.0.255

    Reboot the RPi
   

   sudo shutdown -r now
   

   
   
3. Connecting the Android phone to RPi
   After rebooting RPi, you will see the network name on your phone.
   Connect to the network and make sure the IP is obtained.
   Then, launch the SSH apps and try login RPi.
   I used "ConnectBot" app.
   You can also use "Simple Computer Remote" app to control the RPi once X-server is started.
   
   

Hardware:
    Raspberry Pi
    EW-7781Uh WiFi dongle

    PS Vita Portable Charger 
   
Summary:
RPi is now connected to an Android phone directly without WiFi network.
This will allow me to access to RPi at anywhere.

Reference:     
http://willhaley.com/blog/raspberry-pi-hotspot-ew7811un-rtl8188cus/
http://ariandy1.wordpress.com/2013/04/07/setting-up-wifi-access-point-with-edimax-ew-7811un-on-raspberry-pi/