Sensu plugin for checking number of connections to a port

connection-metrics.sh

#!/bin/bash
#
# Check netstat for number of connections to a specified port
#
# ===
#
# Examples:
#
#   # check by port number
#   connection-metrics.sh -p port
#
# Date: 2015-03-15
# Author: Jesse Rohland <jesse.rohland@gmail.com>
#
# Released under the same terms as Sensu (the MIT license); see LICENSE
# for details.

# get arguments
while getopts 'p:h' OPT; do
  case $OPT in
    p)  PORT=$OPTARG;;
    h)  hlp="yes";;
    *)  unknown="yes";;
  esac
done

# usage
HELP="
    usage: $0 [ -p value -h ]

        -p --> port
        -h --> print this help screen
"

if [ "$hlp" = "yes" ]; then
  echo "$HELP"
  exit 0
fi

if [ ${PORT} ]; then
  conns=`netstat -an | grep ${PORT}`
  
  listen=`echo "$conns" | grep LISTEN | wc -l`
  established=`echo "$conns" | grep ESTABLISHED | wc -l`
  timeout=`echo "$conns" | grep TIME_WAIT | wc -l`
  close=`echo "$conns" | grep CLOSE_WAIT | wc -l`

  hostname=`hostname`
  timestamp=`date +%s`

  echo "${hostname}.conns_${PORT}.listen ${listen} ${timestamp}"
  echo "${hostname}.conns_${PORT}.established ${established} ${timestamp}"
  echo "${hostname}.conns_${PORT}.timeout ${timeout} ${timestamp}"
  echo "${hostname}.conns_${PORT}.close ${close} ${timestamp}"

  exit 0
fi

echo "$HELP"
exit 1