nagios plugin to monitor TCP/UDP connections

check_connections

#!/bin/bash
if [[ $# -ne 2 ]]; then
    echo "WARN and CRIT thresholds not defined"
    exit 3
fi

warn="$1"
crit="$2"

tcp=$(ss -tan | tail -n +3 | egrep -c -v "UNCONN|LISTEN")
udp=$(ss -anu | tail -n +3 | egrep -c -v "UNCONN|LISTEN")
total=$(($tcp + $udp))

if [[ $total -lt $warn ]]; then
    echo "OK TCP $tcp UDP $udp"
    exit 0
fi

if [[ $total -ge $warn && $total -lt $crit ]]; then
    echo "WARN TCP $tcp UDP $udp"
    exit 1
fi

if [[ $total -ge $crit ]]; then
    echo "CRIT TCP $tcp UDP $udp"
    exit 2
fi

echo "UNKNOWN STATUS"
exit 3