In am planning a solo/independent travel tour in the Northern part of Vietnam, but I'm not sure for which part of North Vietnam I do need any permit when traveling by local transport. My itinerary: Hanoi - Hoa Binh - Mai Chau - Moc Chau - Son La - Tuan Giao - Dien Bien Phu - Muong Lay - Muong Te - Lai Chau - Sa pa - Lao Cai - Muang Khuong - Bac Ha - Hanoi. Do I need any permit for these traject? Thanks!