What Product best seal Exterior Steel Rails

Building a front porch and  have steel rails. I need to seal these so they won't rust. Live in So. California, 6 blocks from the beach, and 2 block from the freeway. We will be putting a roof on but I still want the rails protected from the exterior elements. Was going to paint them white but when we got these up I love the steel contrast. 

Any suggestions or experiences would be AWESOME.

Thanks,

Chatty