Monitor and Alert Network Uptime on OpenWrt

OpenWrt is an operating system / embedded operating system based on the Linux kernel and using a command-line interface (ash shell), and a web interface (LuCI) has endless extension possibilities for power users In OpenWrt Monitor network uptime and alert you the downtime can be detected by this script. It will send email notification when a host or site is down

Preview

• [Uptime Monitor] 192.168.1.1 is back up! - Good News -- 192.168.1.1 is back up
• [Uptime Monitor] 192.168.1.1 is down! - Bad News -- 192.168.1.1 is down

Pre-requisites

• fping - similiar to ping, but much better performing when pinging multiple hosts. "How to Install Fping a Ping alternative on Linux"
• msmtp - required for sending email "Send Email with Msmtp on OpenWrt"

Install the script

Step 1: Create the folder and script
cd /etc

mkdir cronscript
cd cronscript
touch uptime_monitor.sh
vi uptime_monitor.sh

Step 2: In vi, You need add this script.

#!/bin/ash
# Uptime monitoring for OpenWrt
# Tested on OpenWrt Attitude Adjustment 12.09 
# Written By justhrun posted on <http://www.techrapid.co.uk>
# ----------------------------------------------------------
# Last Modified : 02/08/2014
# ----------------------------------------------------------

TCHECK=`date "+%Y-%m-%d %H:%M:%S"`
HOSTS="192.168.1.1 192.168.1.4 www.google.com"
xping=/usr/bin/fping
flog=/tmp/log/hostcheck.log
FPATH=/tmp/log
for myHost in ${HOSTS}
do
    filenya=${FPATH}/${myHost}.txt
    if ${xping} -q -t750 ${myHost} ; then
        ## host alive, check then remove file host.txt
        if [ -f ${filenya} ]; then
            echo "${TCHECK} : ${myHost} is BACK UP" >> ${flog}
            echo -e "Subject: [Uptime Monitor] $myHost is back up!\r\n\nGood News -- $myHost is back up" |msmtp --from=default -t destination.address@gmail.com
            rm -f ${filenya}
        fi
    else
        ## host down, check then create file host.txt
        if [ ! -f ${filenya} ]; then
            ## not exist, host is dwon
            echo "${TCHECK} : ${myHost} is DOWN" >> ${flog}
            echo -e "Subject: [Uptime Monitor] $myHost is down!\r\n\nBad News -- $myHost is down" |msmtp --from=default -t destination.address@gmail.com
            touch ${filenya}
        else
            ## exist, still down, logging don't send email
            echo "${TCHECK} : ${myHost} is still DOWN" >> ${flog}
        fi
    fi
  done

#-EOF

Also you can get the script by wget, run following commands:

cd /etc/cronscript
wget http://www.mediafire.com/view/l0xjxk7p9s3p2c5/uptime_monitoring.sh

Configure the script

Step 3: Find and replace which line on the script to your own

# This is address or host that you want to monitor
HOSTS="192.168.1.1 192.168.1.4 www.google.com"

# Path to fping
xping=/usr/bin/fping

# Path where summary log will be created
flog=/tmp/log/hostcheck.log

# Path where host log will be created
FPATH=/tmp/log

# Specify Initial target timeout in millisecond for ping to hosts
-t750

# Specify Subject, Message Body, and Destination Address mail to send when host is backup
echo -e "Subject: [Uptime Monitor] $myHost is back up!\r\n\nGood News -- $myHost is back up" |msmtp --from=default -t destination.address@gmail.com

# Specify Subject, Message Body, and Destination Address mail to send when host is down
echo -e "Subject: [Uptime Monitor] $myHost is down!\r\n\nBad News -- $myHost is down" |msmtp --from=default -t destination.address@gmail.com

Step 4: Test the script to debug the code To test the script run following command:

sh uptime_monitor.sh

If there are no error at testing of the script you can continue to the next step Step 5: Run the script automatically with Cron

1. Select tabs System - Scheduled Tasks
2. Now add it to the column

*/15 * * * * /etc/cronscript/uptime_monitor.sh

It will run the script every 15 minutes or notify you which host is down every 15 Minutes. If you beginner at cron timing you can visit this site: How to Run Cron Every 5 Minutes, Seconds, Hours, Days, Months

Troubleshooting

- OpenWrt report a host when the host is not down

• Slow response time from the host try to increase -t750 to a larger value

References

1. Thanks to justhrun on Kaskus for contributing the code
2. Jetpack Monitor - Mail's template
3. Image by Kishjar on Flickr / CC BY 2.0