Leopard Server Port Mapping?

I just have a quick question. When using an OS X Server machine as a router, can you (finally) set up port mappings through the Server Admin app? Mapping ports is a piece of cake on cheapo hardware routers. I use my file server because it's infinitely more reliable. And boy do I miss my port maps. If you can do them in 10.5, I'm definitely going to have to upgrade.