Automatic wifi router resetter control scripts. Install `thunker` into your `/usr/local/bin` on the RPi and `thunker_daemon` into your *init.d*. You will need Ruby and the `net-ping` and 'wiringpi' gems. See it in action at https://vimeo.com/66365606

thunker

#! /usr/bin/ruby

require 'wiringpi'
require 'net/ping'
require 'syslog'

# Constants
OUTPUT_PINA = 0 # RPi Pin 11
OUTPUT_PINB = 1 # RPi Pin 12
ARM_ON_TIME = 0.1
ARM_RESET_TIME = 0.05
ARM_PAUSE_TIME = 1

# Configs
@logfile_name   = "/var/log/syslog"
@router_ip      = '192.168.5.2'

# Globals
@resetting = false

# Singletons
@gpio = WiringPi::GPIO.new
@pinger = Net::Ping::ICMP.new

##
# Controls the 'organic rotory button actuator'
#
# This should never be calld with HIGH, HIGH or the battery will short out. Both
# pins should be connected to the inputs of a two output H bridge.
def write_bits(a, b)
  if a == HIGH
    raise "Can't have two high bits" if b == HIGH
    # ensure we never have two high bits by always writing LOW first
    @gpio.write OUTPUT_PINB, LOW
    @gpio.write OUTPUT_PINA, HIGH
  else
    # Write out pin values
    @gpio.write OUTPUT_PINA, LOW
    @gpio.write OUTPUT_PINB, b
  end
end

def motor_right
  write_bits(HIGH, LOW)
end

def motor_left
  write_bits(LOW, HIGH)
end

def motor_stop
  write_bits(LOW, LOW)
end

##
# Log a message in the system log so we can keep track of the daemon's actions
def write_to_syslog msg
  Syslog.open 'thunker', Syslog::LOG_PID, Syslog::LOG_DAEMON do |log|
    log.log Syslog::LOG_NOTICE, "%s", msg
  end
end

##
# Check the current status of the wireless network
def wireless_down?
  # Try to ping the router, if we can't after five the wireless is down
  5.times do
    return false if @pinger.ping @router_ip
  end

  true
rescue
  # When the network is unreachable there be errors...
  true
end

##
# Does the router need a slap?
def reset_necessary?
  down = wireless_down?

  # We need to reset if the wireless is down but we aren't yet resetting
  ret = down && !@resetting

  # Log the network comming back up
  write_to_syslog("Network back up") if !down && @resetting

  # Store the state for next time
  @resetting = down
  ret
end

##
# Get the router back up and running
def reset_router
  write_to_syslog("Outage detected.")

  reset_arm
  sleep ARM_PAUSE_TIME
  motor_left
  sleep ARM_ON_TIME
  motor_stop
  sleep ARM_PAUSE_TIME
  reset_arm

  write_to_syslog("Reset complete.")
end

def reset_arm
  motor_right
	sleep ARM_RESET_TIME
	motor_stop
	sleep ARM_RESET_TIME
	motor_right
	sleep ARM_RESET_TIME
	motor_stop
end

##
# It all starts here...
def listener_main

  # Set up the pins to use as an output pin
  @gpio.mode OUTPUT_PINA, OUTPUT
  @gpio.mode OUTPUT_PINB, OUTPUT
  motor_stop

  Signal.trap("TERM") do 
    motor_stop
    exit
  end

  Signal.trap("USR1") do 
    reset_router
  end

  # Listen to the network for failures, with 5 seconds between polls
  loop do
    reset_router if reset_necessary?
    sleep 5
  end
end

# Go!
listener_main

thunker_daemon

#! /usr/bin/env bash

# This is intended for Debain consuption

### BEGIN INIT INFO
# Provides: thunker_daemon
# Required-Start: $all
# Required-Stop:
# Should-Start: $all
# Should-Stop:
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Thunker
# Description: Thunker hits things when wireless drops.
### END INIT INFO

. /lib/lsb/init-functions

exec_name=thunker
exec_path=/usr/local/bin/$exec_name
display_name="Thunker Daemon"

start() {
	pgrep ${exec_name} > /dev/null
	if [ $? -eq 0 ]; then
		log_success_msg "${display_name} is already running"
		return
	fi

	if ${exec_path}&
	then
		disown
		log_success_msg "${display_name} started"
	else
		log_failure_msg "Failed to start ${display_name}"
	fi
}

stop() {
	pkill ${exec_name}
	pgrep ${exec_name} > /dev/null
	if [ $? -ne 0 ]
	then
		log_success_msg "${display_name} stopped"
	else
		log_failure_msg "Failed to stop ${display_name}"
	fi
}

case "$1" in
	start)
		start
		;;
	stop)
		stop
		;;
	restart)
		stop
		start
		;;
	status)
		pid=`pgrep ${exec_name}`
		if [ $? -eq 0 ]
		then
			# All OK
			echo "${display_name} running as PID:$pid."
			exit 0
		else
			# We are not running
			echo "${display_name} is not running."
			exit 3
		fi
		;;
	*)
		echo "Usage: /etc/init.d/thunker_daemon {start|stop|restart|status}"
		exit 1
		;;
esac

exit 0

With thanks to @jstephenson and @tommylommykins