BungeeCord port Forward

so i wanted to know if you had to port forward just Bungee or all of my servers? her is my config

groups:
Mysticforce12345:
- admin
disabled_commands:
- find
player_limit: 60
stats: 05089a34-8c76-412c-97a1-3e0b791f74d2
permissions:
default:
- bungeecord.command.server
- bungeecord.command.list
admin:
- bungeecord.command.alert
- bungeecord.command.end
- bungeecord.command.ip
- bungeecord.command.reload
listeners:
- max_players: 50
fallback_server: Faction
host:...

BungeeCord port Forward