jonschipp-nagios-plugins/check_connections.sh

#!/usr/bin/env bash

# Nagios Exit Codes
OK=0
WARNING=1
CRITICAL=2
UNKNOWN=3

usage()
{
cat <<EOF

Check the number of connections/sockets in a given state.
Uses iproute2's ss tool to retrieve connections.

     Options:
        -s         State of connection (def: all)
		   (established, syn-sent, syn-recv, fin-wait-1, fin-wait-2, time-wait,
			closed, close-wait, last-ack, listen, and closing)
	-f 	   Apply quoted ss expression filter e.g. '( dst 192.168.1/24 and dport >= :1024 )'
	-p <type>  Set protocol or family type (udp/tcp/inet/inet6)
        -c         Critical threshold as an integer
        -w         Warning threshold as an integer

Usage: $0 -s established '( sport = :443 )' -w 800 -c 1000
EOF
}

argcheck() {
# if less than n argument
if [ $ARGC -lt $1 ]; then
        echo "Missing arguments! Use \`\`-h'' for help."
        exit 1
fi
}

if ! command -v ss >/dev/null 2>&1; then
	echo -e "ERROR: ss is not installed or not found in \$PATH!"
	exit 1
fi

# Define now to prevent expected number errors
STATE=all
CRIT=0
WARN=0
COUNT=0
ARGC=$#
CHECK=0

argcheck 1 

while getopts "hc:s:f:p:w:" OPTION
do
     case $OPTION in
         h)
	     usage
             ;;
         s)
             STATE="$OPTARG"
	     CHECK=1
             ;;
         f)
 	     FILTER="$OPTARG"
	     CHECK=1
             ;;
	 p)
	     if [[ $OPTARG == tcp ]]; then
                PROTOCOL="-t"
             elif [[ $OPTARG == udp ]]; then
                PROTOCOL="-u"
             elif [[ $OPTARG == inet ]]; then
                PROTOCOL="-4"
             elif [[ $OPTARG == inet6 ]]; then
                PROTOCOL="-6"
             else
                echo "Error: Protocol or family type no valid!"
		exit 1
             fi
	     CHECK=1
	     ;; 
         c)
	     CRIT="$OPTARG"
	     CHECK=1
             ;;
	 w) 
	     WARN="$OPTARG"
	     CHECK=1
	     ;;
         \?)
             exit 1
             ;;
     esac
done

COUNT=$(ss -n state $STATE $PROTOCOL $FILTER | grep -v 'State\|-Q' | wc -l)

if [ $COUNT -gt $CRIT ]; then
        echo "$COUNT sockets in $STATE state!"
        exit $CRITICAL
elif [ $COUNT -gt $WARN ]; then
        echo "$COUNT sockets in $STATE state!"
        exit $WARNING
else
        echo "$COUNT sockets in $STATE state."
        exit $OK
fi