findRaspis.sh

#!/bin/bash
#######################################################################################################################
#
#   Find all existing Raspberries in local subnet
#
#   Search for mac addresses used by Raspberries which are defined on
#   https://udger.com/resources/mac-address-vendor-detail?name=raspberry_pi_foundation
#
#######################################################################################################################
#
#    Copyright (c) 2021-2024 framp at linux-tips-and-tricks dot de
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
#######################################################################################################################

set -euo pipefail

VERSION=0.7.1
GITREPO="https://github.com/framps/raspberryTools"

MYSELF="$(basename "$0")"
MYNAME=${MYSELF%.*}
S_OPTIONARGS="imhd"

# check for required commands and required bash version

if ! command -v nmap COMMAND &> /dev/null; then
	echo "Missing required program nmap."
	exit 255
fi

if ! command -v host COMMAND &> /dev/null; then
	echo "Missing required program host."
	exit 255
fi

if (( BASH_VERSINFO[0] < 4 )); then
    echo "Minimum bash 4.0 is required. You have $BASH_VERSION."
    exit 255
fi

# define defaults

# See https://www.ipchecktool.com/tool/macfinder for MACs

DEFAULT_SUBNETMASK="192.168.0.0/24"
DEFAULT_MAC_REGEX="28:cd:c1|2c:cf:67|b8:27:eb|d8:3a:dd|dc:a6:32|e4:5f:01"
# see https://udger.com/resources/mac-address-vendor-detail?name=raspberry_pi_foundation
INI_FILENAME=/usr/local/etc/${MYNAME}.conf

# help text

if (( $# >= 1 )) && [[ "$1" =~ ^(-h|--help|-\?)$ ]]; then
    cat << EOH
$MYSELF $VERSION ($GITREPO)

Usage:
    $MYSELF                       Scan subnet $DEFAULT_SUBNETMASK for Raspberries sorted by IP
    $MYSELF -n <subnetmask>       Scan subnet for Raspberries
    $MYSELF -s [i|m|h|d]             Sort for IPs, Macs, Hostnames or description, Default: IP
    $MYSELF -h | -? | --help      Show this help text

Defaults:
    Subnetmask: $DEFAULT_SUBNETMASK
    Mac regex:  $DEFAULT_MAC_REGEX

Example:
    $MYSELF -n 192.168.179.0/24 -s m

Init file $INI_FILENAME can be used to customize the mac address scan and descriptions.
First optional line can be the regex for the macs to scan. See default below for an example.
All following lines can contain a mac and a description separated by a space to add a meaningful
description to the system which owns this mac. Otherwise the hostname discovered will used as the description.

Example file contents for $INI_FILENAME:
    b8:27:eb|dc:a6:32|e4:5f:01
    b8:27:eb:b8:27:eb VPN Server
    b8:27:eb:b8:28:eb Web Server

EOH
    exit 0
fi

set +e
sortType="$(grep -o "\-s [$S_OPTIONARGS]" <<< "$@")"
set -e
[[ -z $sortType ]] && sortType="-s i"

set +e
network="$(grep -E -o '\-n \S+' <<< "$@")"
set -e
if [[ -z $network ]]; then
    network="$DEFAULT_SUBNETMASK"
else
    network=$(cut -f2 -d" " <<< $network)
fi

# read property file with mac regexes

MY_MAC_REGEX="$DEFAULT_MAC_REGEX"

if [[ -f "$INI_FILENAME" ]]; then
    MY_MAC_REGEX_FROM_INI="$(head -n 1 "$INI_FILENAME" | awk '{print $2}')"
    if [[ -z "$MY_MAC_REGEX_FROM_INI" ]]; then
        MY_MAC_REGEX="$(head -n 1 "$INI_FILENAME")"
    fi
fi
MY_MAC_REGEX=" (${MY_MAC_REGEX})"

# define associative arrays for mac and hostname lookups

declare -A macAddress=()

echo "$MYSELF $VERSION ($GITREPO)"
echo "Scanning subnet $network for Raspberries ..."

# scan subnet for Raspberry macs

# 192.168.0.12             ether   dc:a6:32:8f:28:fd   C                     wlp3s0 -
while read -r ip dummy mac rest; do
    macAddress["$ip"]="$mac"
done < <(nmap -sP "$network" &>/dev/null; arp -n | grep -Ei " $MY_MAC_REGEX")

tmp=$(mktemp)

# retrieve and print hostnames

if (( ${#macAddress[@]} > 0 )); then

    maxHostnameLen=0
    maxDescriptionLen=0

    for ip in ${!macAddress[@]}; do
        set +e
        h="$(host "$ip")"
        rc=$?
        set -e
        host=""
        if (( ! rc )); then
            # 12.0.168.192.in-addr.arpa domain name pointer asterix.
            read -r arpa dummy dummy dummy host rest <<< "$h"
            host=${host::-1} # delete trailing "."
        fi

        if [[ -z "$host" ]]; then
            host="Unknown"
        fi

        if [[ -f "$INI_FILENAME" ]]; then
            set +e
            hostDescription="$(grep -i "${macAddress[$ip]}" "$INI_FILENAME")"
            rc=$?
            set -e
            if (( ! rc )); then
                hostDescription="$(cut -f 2- -d ' ' <<< "$hostDescription" | sed 's/^ *//; s/ *$//')"
            else
                hostDescription=""
            fi
        else
            hostDescription="n/a"
        fi

        (( maxHostnameLen < ${#host} )) && maxHostnameLen=${#host}
        (( maxDescriptionLen < ${#hostDescription} )) && maxDescriptionLen=${#hostDescription}

        printf "%s %s %s %s\n" "$ip" "${macAddress[$ip]}" "$host" "$hostDescription" >> $tmp
    done

    printf "\n%-15s %-17s %-${maxHostnameLen}s %-${maxDescriptionLen}s\n" "IP address" "Mac address" "Hostname" "Description"   

    sort=$(cut -f 2 -d " " <<< "$sortType")
    if [[ $sort == "i" ]]; then
        sortCmd="sort -t . -k 1,1n -k 2,2n -k 3,3n -k 4,4n"
    else
        key=$(grep -aob "$sort" <<< "$S_OPTIONARGS"| grep -oE '[0-9]+')
        ((key++))
        sortCmd="sort -k $key"
    fi

    while read -r ip mac host desc ; do
        printf "%-15s %-17s %-${maxHostnameLen}s %-${maxDescriptionLen}s\n" "$ip" "$mac" "$host" "$desc"
    done < <($sortCmd $tmp)

else
    echo "No Raspberries found with mac regex $MY_MAC_REGEX"
fi

rm $tmp