Server Health Check port ssh

Where you are see these log "Did not receive identification string"? F5 or Server?

Refer below URL for basic external monitor. https://devcentral.f5.com/articles/ltm-external-monitors-the-basics

Please customize sample external monitor script.

     remove IPv6/IPv4 compatibility prefix (LTM passes addresses in IPv6 format)
    IP=`echo ${1} | sed 's/::ffff://'`
    PORT=${2}

    PIDFILE="/var/run/`basename ${0}`.${IP}_${PORT}.pid"
     kill of the last instance of this monitor if hung and log current pid
    if [ -f $PIDFILE ]
    then
    kill -9 `cat $PIDFILE` > /dev/null 2>&1
        fi
    echo "$$" > $PIDFILE

         send request & check for expected response
    curl -fNs -m ${P_TIMEOUT} http://${IP}:${PORT}${URI} | grep -i "${RECV}" 2>&1 > /dev/null

     let bigd mark node UP if expected response was received
     otherwise force the node DOWN immediately
    if [ $? -eq 0 ]
    then
    echo "UP"
        else
    /bin/bigpipe pool ${POOL} member ${IP}:${PORT} down 2>&1 > /dev/null
        fi

    rm -f $PIDFILE
        exit

Let us know if require any help to customize above script.