AFN is a repackage of various US networks' programming, designed for viewing by US servicemembers stationed overseas. From their website:
"Eligible AFN viewers can purchase or lease decoders from their local Army and Air Force Exchange Service or Navy Exchange Service Command stores. Because of the need to personally verify the eligibility of purchasers, all purchases must be accomplished in person.
The authorized viewers of the American Forces Radio and Television Service (AFRTS) are limited to: active duty military assigned/deployed overseas; direct-hire Department of Defense and Department of State employees serving overseas; military retirees living overseas; and, the family members accompanying these personnel overseas.
The authorized audience limitations are imposed on AFRTS by the program owners and distributors who provide their programming to AFRTS at little or no cost, but who's primary interests are to sell their programming to commercial broadcasting, cable, and satellite distributors worldwide. "
It is not legal to receive this programming unless you fit into those catagories. Military in the US, with a couple of exceptional posts, watch the local television stations and regular "cable" networks like ESPN, etc.