#!/bin/bash
# the most basic "host discover" networking script using ping

### input format:

# $1 = SUBNET e.g. 192.168.0
# $2 = RANGE e.g. 255

### output format:
# ip                            (mac)                                   (hostname)                                                      (real/vm)       description & howto

SUBNET=192.168.1
RANGE=255
LOGFILE="scan_network_device_simple_ping.$SUBNET.log"
CURRENT_MAC=""
CURRENT_IP=""
CURRENT_HOSTNAME=""


echo "===== scan_network_device_simple_ping v1 ====="

echo "=== starting new log file $LOGFILE ==="
echo "ip                (mac)           (hostname)      (real/vm)       description & howto" > $LOGFILE;

echo "ping scanning SUBNET: "$SUBNET;
echo "ping scanning RANGE: "$RANGE;

echo "=== start scan ==="

for ((n=1; n<=$RANGE; n++))
do
        # assemble ip
        CURRENT_IP=$SUBNET.$n;

        echo "=== test if host is alive (3x pings) ==="

        ping -c1 $CURRENT_IP

        echo "=== test if a mac address was discovered ==="

        CURRENT_MAC=$(arp -n -a|grep $CURRENT_IP)
        sleep 1; # chance to Ctrl+C cancel the process

        if [[ $CURRENT_MAC == *"incomplete"* ]];
        then
                CURRENT_MAC="unkown";
        fi

        echo "=== test if hostname can be resolved ==="

        CURRENT_HOSTNAME_TEMP=$(host $CURRENT_IP)

        if [[ $CURRENT_HOSTNAME_TEMP == *"not found"* ]];
        then
                CURRENT_HOSTNAME="unkown";
        else
                CURRENT_HOSTNAME=$(echo $CURRENT_HOSTNAME_TEMP|grep -oE '[^ ]+$')
        fi

        # ip                    (mac)           (hostname)              (real/vm)       description & howto
        echo "$CURRENT_IP       ($CURRENT_MAC)  ($CURRENT_HOSTNAME)     (real/vm?)      description & howto" >> $LOGFILE;
done