mac_vendors.rb

#!ruby

mac_vendors = Hash.new

File.open('./oui.txt') do |f|
  array = f.readlines
  array.each do |e|
    next unless e =~ /\(hex\)/
    k, v = e.split(/\(hex\)/)
    mac_vendors.store(k&.gsub(/-/, ':')&.strip&.upcase, v&.strip)
  end
end

mac_addrs = Array.new

$stdin.each_line do |l|
  next unless l =~ /DHCPACK/
  mac_addr = l.match(/([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})/).to_s
  mac_addrs << mac_addr.upcase
end

uniq_mac_addrs = mac_addrs.uniq
appeared_mac_vendors = Array.new

uniq_mac_addrs.each do |mac|
  appeared_mac_vendors << (mac_vendors[mac[0..7]] || "unknown (#{mac[0..7]})")
end

count = Hash.new(0)
appeared_mac_vendors.each do |e|
  count[e] += 1
end

count.sort.reverse.sort_by{|k,v| v}.reverse.each do |k,v|
  printf "%4d\t%s\n", v, k
end