ips_from

# File actionpack/lib/action_dispatch/middleware/remote_ip.rb, line 149
      def ips_from(header)
        # Split the comma-separated list into an array of strings
        ips = @env[header] ? @env[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