shell script for monitoring WAN staus on router and sending pushover notifications

wan_monitor.sh

#!/bin/sh
# This script checks for internet connectivity on your wan port and sends a pushover message if there has been a change.
# Multiple WAN ports supported.
# Based on Scripts from Wob_76 & WaLLy3K at http://www.linksysinfo.org/index.php?threads/wan-up-down-notifications-script-multiwan.73057/

# Set the Number of WANS (Valid Numbes 1 to 4)
WANS=2

# Name your ISPs 
WAN1_name="Excitel"
WAN2_name="Airtel"

# set pushover credentials
po_token="xxx"
po_user="xxx"

# get the gateway IP for pppoe or dhcp connection
get_gateway() {
  local gw=$(nvram get wan${wannum}_gateway_get)
  if [ "$gw" != "0.0.0.0" ]; then
    echo $gw
  else
    echo $(nvram get  wan${wannum}_gateway)
  fi
}

notify_admin() {
    # get the gateway address
    wan_gateway=$(get_gateway)
    # ping the gateway to test connectivity
    ping_test=$(ping -c1 -W1 -w3 "$(echo $wan_gateway)" &> /dev/null; echo $?)
    # update message, priority and log based on the result of the test
    if [ "$ping_test" -ne 0 ]; then
      logger -st "[INFO]" "$isp_name offline"
      msg="$isp_name has gone offline!"
      p="1"
      wan_status="offline"
    else
      logger -st "[INFO]" "$isp_name online"
      msg="$isp_name is now online :)"
      p="0"
      wan_status="online"
    fi
    # set file name for saving connection status
    WAN_STATUS_FILE=/tmp/wan${wannum}_status
    # get last connection status, if file exists
    if [ -f $WAN_STATUS_FILE ]; then
      WAN_LAST_STATUS=$(cat $WAN_STATUS_FILE)
    else
      WAN_LAST_STATUS=
    fi
    # if status has changed, send notification
    if [ $wan_status != "$WAN_LAST_STATUS" ]; then
      echo $wan_status > $WAN_STATUS_FILE
      # send notification via pusher
      push_msg=$(curl -s -F "token=$po_token" -F "user=$po_user" -F "message=$msg" \
        -F "title=$HOSTNAME Router" -F "priority=$p" \
        -F "retry=300" -F "expire=600" http://api.pushover.net/1/messages.json)
      push_status=$(echo "$push_msg" | grep -c "status\":1")
      # log error if unable to send notification
      if [ "$push_status" -ne 1 ]; then
        logger -st "[ERROR]" "Unable to send notification via Pushover"
        push_error=$(echo "$push_msg" | sed 's/^.*\("errors":.*"]\).*$/\1/' | cut -d\" -f4)
        [ -n "$push_error" ] && logger -st "[ERROR]" "$push_error"
      fi
    fi
  }

for num in $(seq 1 $WANS); do
  if [ ${num} == 1 ]; then
    wannum=""
  else
    wannum=${num}
  fi
  # set isp name
  eval isp_name="\$WAN${num}_name"
  notify_admin
done