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#!/bin/bash
#Copyright Angsuman Chakraborty, Taragana. Permission is granted for personal, non-commercial use.
#The script may not be re-distributed in any form without written permission from Angsuman Chakraborty ( angsuman@taragana.com ).
#The script may be modified for personal use.
#THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE AUTHOR ACCEPTS NO RESPONSIBILITY IN ANY CONCEIVABLE MANNER.
# Conventionally 0 indicates success in this script.
# Time between checks in seconds
SLEEPTIME=10
#IP Address or domain name to ping. The script relies on the domain being
#pingable and always available
TESTIP=www.yahoo.com
#Ping timeout in seconds
TIMEOUT=2
# External interfaces
EXTIF1=eth0
EXTIF2=ra0
#IP address of external interfaces. This is not the gateway address.
IP1=192.168.1.104
IP2=192.168.0.103
#Gateway IP addresses. This is the first (hop) gateway, could be your router IP
#address if it has been configured as the gateway
GW1=192.168.1.1
GW2=192.168.0.1
# Relative weights of routes. Keep this to a low integer value. I am using 4
# for TATA connection because it is 4 times faster
W1=1
W2=1
# Broadband providers name; use your own names here.
NAME1=linksys
NAME2=newbies
#No of repeats of success or failure before changing status of connection
SUCCESSREPEATCOUNT=4
FAILUREREPEATCOUNT=1
# Do not change anything below this line
# Last link status indicates the macro status of the link we determined. This is down initially to force routing change upfront. Don't change these values.
LLS1=1
LLS2=1
# Last ping status. Don't change these values.
LPS1=1
LPS2=1
# Current ping status. Don't change these values.
CPS1=1
CPS2=1
# Change link status indicates that the link needs to be changed. Don't change these values.
CLS1=1
CLS2=1
# Count of repeated up status or down status. Don't change these values.
COUNT1=0
COUNT2=0
while : ; do
sudo ping -W $TIMEOUT -I $IP1 -c 1 $TESTIP > /dev/null 2>&1
RETVAL=$?
if [ $RETVAL -ne 0 ]; then
echo $NAME1 Down
CPS1=1
else
CPS1=0
fi
if [ $LPS1 -ne $CPS1 ]; then
echo Ping status changed for $NAME1 from $LPS1 to $CPS1
COUNT1=1
else
if [ $LPS1 -ne $LLS1 ]; then
COUNT1=`expr $COUNT1 + 1`
fi
fi
if [[ $COUNT1 -ge $SUCCESSREPEATCOUNT || ($LLS1 -eq 0 && $COUNT1 -ge $FAILUREREPEATCOUNT) ]]; then
echo Uptime status will be changed for $NAME1 from $LLS1
CLS1=0
COUNT1=0
if [ $LLS1 -eq 1 ]; then
LLS1=0
else
LLS1=1
fi
else
CLS1=1
fi
LPS1=$CPS1
sudo ping -W $TIMEOUT -I $IP2 -c 1 $TESTIP > /dev/null 2>&1
RETVAL=$?
if [ $RETVAL -ne 0 ]; then
echo $NAME2 Down
CPS2=1
else
CPS2=0
fi
if [ $LPS2 -ne $CPS2 ]; then
echo Ping status changed for $NAME2 from $LPS2 to $CPS2
COUNT2=1
else
if [ $LPS2 -ne $LLS2 ]; then
COUNT2=`expr $COUNT2 + 1`
fi
fi
if [[ $COUNT2 -ge $SUCCESSREPEATCOUNT || ($LLS2 -eq 0 && $COUNT2 -ge $FAILUREREPEATCOUNT) ]]; then
echo Uptime status will be changed for $NAME2 from $LLS2
CLS2=0
COUNT2=0
if [ $LLS2 -eq 1 ]; then
LLS2=0
else
LLS2=1
fi
else
CLS2=1
fi
LPS2=$CPS2
if [[ $CLS1 -eq 0 || $CLS2 -eq 0 ]]; then
if [[ $LLS1 -eq 1 && $LLS2 -eq 0 ]]; then
echo Switching to $NAME2
ip route replace default scope global via $GW2 dev $EXTIF2
elif [[ $LLS1 -eq 0 && $LLS2 -eq 1 ]]; then
echo Switching to $NAME1
ip route replace default scope global via $GW1 dev $EXTIF1
elif [[ $LLS1 -eq 0 && $LLS2 -eq 0 ]]; then
echo Restoring default load balancing
ip route replace default scope global nexthop via $GW1 dev $EXTIF1 weight $W1 nexthop via $GW2 dev $EXTIF2 weight $W2
fi
fi
sleep $SLEEPTIME
done