Amendements to TVRouter article of July 2013

One of the first articles I wrote on this site concerned using a Raspberry Pi to act as a wifi to ethernet router to enable my (then) TV set to connect to the internet via my main WiFi router. The tv set had an ethernet port, but it was not convenient to wire it to the router by cable. It turned out to be the second most popular post I have written, and has attracted many comments since it was first written in July 2013. Since then the Raspian distro has been improved and altered quite a bit.
Recently I received a comment from a reader who was having problems getting the project to work on the latest distro, and since I had not looked at it for some time, I decided to try a fresh install (on a Pi2) using the latest distro available. Sure enough I found that I too had problems. It appeared that the wlan0 interface did not initialise correctly.
I did some research on the internet and came across an interesting article at http://raspberrypi.stackexchange.com/questions/9678/static-ip-failing-for-wlan0 which appeared to be very relevant. I tried out the wlan0-restart script which was one of the suggested solutions and found that it cured the problem.

I reproduce the script here

 #!/bin/sh
#
#

### BEGIN INIT INFO
# Provides:          wlan0-restart
# Required-Start:    $network
# Required-Stop:     $network
# Should-Start:
# Should-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Restarts wlan0 interface
# Description:       Restarts wlan0 interface to fix problem with static address in WiFi AP
# X-Start-Before:    hostapd isc-dhcp-server
### END INIT INFO

PATH=/sbin:/usr/sbin:$PATH

do_start() {
  ifdown wlan0
  ifup wlan0
}

case "$1" in
  start)
    do_start
    ;;
  restart|reload|force-reload)
    echo "Error: argument '$1' not supported" >&2
    exit 3
    ;;
  stop)
    ;;
  status)
    ;;
  *)
    echo "Usage: $0 start|stop" >&2
    exit 3
    ;;
esac
exit 0

To set this up, use the nano editor and create the file
sudo nano /etc/init.d/wlan0-restart
with the content above.
You should then set it to be executable
sudo chmod 755 /etc/init.d/wlan0-restart
It is important that this is executed BEFORE the isc-dhcp server is started
so to ensure that this is the case, if you have already installed isc-dhcp-server as per the original article, you should first disable it by typing:
sudo update-rc.d isc-dhcp-server remove
then set up the new wlan0-restart script with
sudo update-rc.d wlan0-restart defaults
before setting up the isc-dhcp server again with
sudo update-rc.d isc-dhcp-server defaults

If you follow the quick install method using the tvrouter.zip file, you can setup the wlan0-restart script at point 8a, BEFORE installing the isc-dhcp-server, then you will not have to remove it with update-rc.d and reset it again, but merely use update-rc.d to setup the wlan0-reset script.

Hopefully this should enable the project to work with the latest Raspian distribution again as it is currently doing on my Pi2. You will see some error messages on the screen when the script is invoked, but you can ignore these as it does work.! When the boot process has completed you should see two ip addresses listed on the screen. The first will be the ethernet address (192.168.2.1) and the second the wlan0 address (192.168.1.98)
All being well, you should be able to log on and ping your mail wireless router (probably on 192.168.1.1) and your tv (or laptop) connected to the ethernet port which will probably have been served the ip address 192.168.2.10. Remember if you use a different address for the wlan0 port you will have to rebuild the iptables as discussed in the original article.

Two final points. First, the quick install does NOT point out that you SHOULD alter the interfaces file once you have installed it to reflect your own ssid and password

Secondly, many people have asked me if it is possible to use the project with dlna devices. to access media content. Unfortunately it was not designed with this in mind, and dlna will not easily work across a router (which is what this project is!) as it is designed for use on a single local network, relying on broadcast signals. I have read many articles looking at this problem but have not seen a satisfactory solution to this yet, so don’t ask me! Of course if you know how it can be done, I and many others would love to know.