EnsurePublicSetup create the public setup, it's okay to have inf == nil.

GetCurrentPublicExitLink basically find how the public bridge (br-pub) is wired to the outside world.

GetPrivateExitLink returns the physical link zos is wired to.

GetPublicSetup gets the public setup from reality or error if node has no public setup.

IPs gets the public ips of the nodes.

LoadPublicConfig loads public config from file.

SavePublicConfig stores public config in a file.

SetPublicExitLink rewires the br-pub to a different exit (upstream) device.

PublicBridge public bridge name, exists only after a call to EnsurePublicSetup.

ErrNoPublicConfig is the error returns by ReadPubIface when no public interface is configured.