Nagios plugin to look for incast sockets

check_incast_socket.sh

#!/bin/sh

SENDQ_SIZE=65536

_parse_netstat()
{
        netstat -p tcp -n | awk 'BEGIN { count = 0 }
                {
                        if($6 == "ESTABLISHED" && $3 >= threshold)
                        {
                                output = sprintf("sendq=%s foreignaddress=%s ", $3, $5)
                                count = count + 1
                        }
                }

                END {
                        if(count > 0)
                        {
                                printf("CRITICAL - %s", output)
                                exit 2
                        }
                        else
                        {
                                printf("%s", "OK")
                                exit 0
                        }

        }' threshold=${SENDQ_SIZE}
        return $?
}

_main()
{
        _parse_netstat
        exit $?
}

_main