A slice of Kimchi - IT Security Blog

Hello,

In order to help a friend to monitor his webservices, I have written a small tool to check the availability of the different webservices.

The script is used with crontab and the Freemobile API provides the possibility to send free SMS (free as a free beer). You can choose if you prefer SMS alerts, email alerts or both. It checks the HTTP return code of the webpages : anything other than 200 will trigger the alert.

You have to edit: - ALERT_SMS_API - ALERT_EMAIL - LOGFILE - use_sms=y (by default, yes) - use_email=y (by default, yes)

#!/bin/sh

# apt-get install screen curl mailutils

URL=$1

ALERT_SMS_API="https://smsapi.free-mobile.fr/sendmsg?user=USERID_FIXME&pass=PASSWORD_FIXME&msg="
ALERT_EMAIL="email@email0.com_FIXME email@email1.com_FIXME"
LOGFILE=/home/availability/alert.log

use_sms=y
use_email=y


umask 077

if [ ! $1 ]; then
  echo "usage $0 http://www.url.to/test"
  exit 1
fi

if [ ! -f "${LOGFILE}" ]; then
  touch "${LOGFILE}"
fi



alert() {
  current_date=$(date "+%Y-%m-%d %H:%m:%S")
  msg="${current_date} - ALERT on $1"

  echo "${msg} - alert()" >> ${LOGFILE}

  if [ ${use_sms} = "y" ]; then
    curl -sL -o /dev/null --insecure "${ALERT_SMS_API}${msg}"
    echo "${msg} - sms sent" >> ${LOGFILE}
  fi

  if [ ${use_email} = "y" ]; then
    for j in ${ALERT_EMAIL}
    do
      echo "${msg}" | mail -s "${msg}" ${j}
      echo "${msg} - email sent to ${j}" >> ${LOGFILE}
    done
  fi
}


curl 2>/dev/null >/dev/null
if [ $? -ne 2 ]; then
  alert "curl not found"
  exit
fi

output=$(curl -sL -w "%{http_code}\n" "$1" -o /dev/null --connect-timeout 5)

if [ $? -ne 0 ]; then
  alert ${URL}
  exit
fi

if [ "X${output}" != "X200" ]; then
  alert ${URL}
  exit
fi

The crontabs to check the webservices every 5 minutes are:

*/5   *    *    *    *    /home/availability/alert-availability.sh http://domain.com/path/to/webservice0
*/5   *    *    *    *    /home/availability/alert-availability.sh http://domain.com/path/to/webservice1
*/5   *    *    *    *    /home/availability/alert-availability.sh http://domain.com/path/to/webservice2
*/5   *    *    *    *    /home/availability/alert-availability.sh http://domain.com/path/to/webservice3

This tool was tested on a Debian 7.6. So you need perhaps to run apt to install the necessary packages:

apt-get install curl mailutils

You can see the past alerts as entries in the logfile:

2015-05-01 13:10:02 - ALERT on http://www.XXX.XXX/status/XXXX - alert()
2015-05-01 13:10:02 - ALERT on http://www.XXX.XXX/status/XXXX - sms sent
2015-05-01 13:10:02 - ALERT on http://www.XXX.XXX/status/XXXX - email sent to email@email0.com_FIXME
2015-05-01 13:10:02 - ALERT on http://www.XXX.XXX/status/XXXX - email sent to email@email1.com_FIXME