#!/usr/local/bin/bash
#
# check_netstat_combined - Nagios netstat check script (perfdata only)
# version 1.0   15.11.2012
# by Mikanoshi - iam@mikanoshi.name, http://en.mikanoshi.name
# tested on FreeBDS 8.3
#
# This Nagios plugin is free software, and comes with ABSOLUTELY NO WARRANTY.
# It may be used, redistributed and/or modified under the terms of the
# GNU General Public Licence (see http://www.fsf.org/licensing/licenses/gpl.txt).

STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3

GET_CONN=FALSE
GET_PORTS=FALSE
NETSTAT="/usr/local/libexec/nagios/netstat"
AWK=`which awk 2>/dev/null`

function usage {
	printf "\nUsage: check_netstat_combined [-c] [-p <ports>]\n"
	printf " -c		Connections per second (requested, accepted, failed, established)\n"
	printf " -p <ports>	Comma-separated list of ports, e.g.:\n		check_netstat_combined -p 80,8080,21,25\n"
}

while getopts p:ch argcase "$@"
do
	case $argcase in
		c)	GET_CONN=TRUE;;
		p)	GET_PORTS=TRUE
			PORTS=($OPTARG);;
		h)	usage
			exit;;
	esac
done

if [[ $GET_CONN = "FALSE" && $GET_PORTS = "FALSE" ]] ; then
	usage
	exit $STATE_UNKNOWN
fi

printf "OK - data received |"

if [ $GET_CONN = "TRUE" ] ; then
	$NETSTAT -s 2>/dev/null | awk '
	/connection requests/ { printf " conn_requested="$1"c;;;" }
	/connection accepts/  { printf " conn_accepted="$1"c;;;" }
	/bad connection/      { printf " conn_failed="$1"c;;;" }
	/connections established/ { printf " conn_established="$1"c;;;\n" }'
fi

if [ $GET_PORTS = "TRUE" ] ; then
	$NETSTAT -nptcp 2>/dev/null | egrep -v 'Active|Address|sockets' | $AWK '{print ($4)}' | cut -d. -f 5 | sort | uniq -ci | sort | \
	$AWK -v ports="$PORTS" 'BEGIN { split(ports, portsarr, ",") } { for (i in portsarr) if (portsarr[i] == $2) printf " port%s=%s;;;",$2,$1 }'
	printf "\n"
fi

exit $STATE_OK