valid_v4?

# File lib/ipaddr.rb, line 28
    def valid_v4?(addr)
      if /\A(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\Z/ =~ addr
        return $~.captures.all? {|i| i.to_i < 256}
      end
      return false
    end