ips_from

# File actionpack/lib/action_dispatch/middleware/remote_ip.rb, line 158
      def ips_from(header) # :doc:
        return [] unless header
        # Split the comma-separated list into an array of strings
        ips = header.strip.split(/[,\s]+/)
        ips.select do |ip|
          begin
            # Only return IPs that are valid according to the IPAddr#new method
            range = IPAddr.new(ip).to_range
            # we want to make sure nobody is sneaking a netmask in
            range.begin == range.end
          rescue ArgumentError
            nil
          end
        end
      end