Scan Network for Unknown Computers

#!/bin/bash

if [[ $EUID -ne 0 ]]; then
  echo "You must be a root user"
  echo "Trying to restart script as sudo"
  sudo $0 $@
  exit
fi

#Color codes
bold=`echo -en "\e[1m"`
underline=`echo -en "\e[4m"`
red=`echo -en "\e[31m"`
blue=`echo -en "\e[34m"`
normal=`echo -en "\e[0m"`
blink=`echo -en "\e[5m"`
purple=`echo -en "\e[35m"`
reverse=`echo -en "\e[7m"`

#tmp files
list="/tmp/maclist"
found="/tmp/macfound"
unknown="/tmp/macunknown"
scan="/tmp/macscan"

rm "$list" "$found" "$unknown" "$scan"
touch "$list" "$found" "$unknown" "$scan"

#Known List URL
url="http://filmsbykris.com/personal/home/maclist.php?key=shopp3r"

clear

echo "Downloading list..."
wget -q "$url" -O $list

echo "Scanning Network..."
arp-scan -l > $scan
cat $scan|\
  awk '{print $2}'|\
  grep ':'|\
  while read l;
  do
    grep -i "$l" $list >> $found||echo "$l" >> $unknown
  done

echo -e "\n\n${bold}${underline}Recognized Machines${normal}"
cat $found |while read l
do
  IFS=' ' read -r -a a <<< "$l"
  ip="$(grep -i "${a[2]}" $scan|awk '{print $1}' )"
  echo -n "${blue}"
  echo -n "${a[0]} "
  echo -n "${normal}${bold}${purple}"
  echo -n "$ip "
  #echo -n "${a[1]} "
  echo -n "${normal}${bold}"
  echo -n "${a[2]}"
  echo "${normal}"
done|column -t

echo -e "\n\n${red}${underline}Unknown Machines${normal}"
cat $unknown|while read l
do
  s="$(grep -i "$l" $scan)"
  IFS=' ' read -r -a a <<< "$s"
  echo -n "${bold}${blink}${red}${reverse}"
  echo -n "${a[0]}"
  echo -n "${a[1]}"
  echo "${normal}"
done