Permits into the NPs or NFs? As far as I can tell, NF Rec permits aren't restricted the same way an NP permit often is. In fact, I think you can buy an annual pass to all the NFs in the entire US.
Edit: Should specify, those NF permit fees are for recreational use, and its more for areas that have bathrooms and other day use things. I don't believe you need a permit to hike in a National Forest, but you do need a permit for some things, like using a campground or importantly starting a fire.