Grep MAC and IP address using Regular expression

• MAC Address
  grep -o -E "([[:xdigit:]]{1,2}:){5}[[:xdigit:]]{1,2}" found.txt
• IP Address
  grep -o -E "([0-9]{1,3}[\.]){3}[0-9]{1,3}" found.txt

[\.] looks for a literal period.
  ([0-9]{1,3}[\.]) can find the first octet.
  {3} three occurrences of the previous expression.
  [0-9]{1,3} is a manual addition of the fourth octet

Grep known IPs

• Starting with 192.x.x.x
  cat nmap.txt | grep -E "(192)(\.[0-9]{1,3}){3}"
• Starting with 192.168.x.x
  cat nmap.txt | grep -E "(192.168)(\.[0-9]{1,3}){2}"
• Starting with 192.168.32.x
  cat nmap.txt | grep -E "(192.168.32.)[0-9]{1,3}"

IP and MAC on 1 line

• nmap + awk
  sudo nmap -sn 172.31.201.0/24 | awk '/Nmap scan report for/{printf $5;}/MAC Address:/{print " => "$3;}' | sort