optimize: allow to bind nothing

cmd/run.go

@@ -150,7 +150,7 @@ func newControlPlane(log *logrus.Logger, bpf interface{}, conf *config.Config) (
 	}
 
 	if len(conf.Global.LanInterface) == 0 && len(conf.Global.WanInterface) == 0 {
-		return nil, fmt.Errorf("LanInterface and WanInterface cannot both be empty")
+		log.Warnln("No binding interface.")
 	}
 
 	// Deep copy a conf to avoid modification.

control/bpf_utils.go

@@ -178,8 +178,6 @@ func (p bpfIfParams) CheckVersionRequirement(version *internal.Version) (err err
 type loadBpfOptions struct {
 	PinPath           string
 	CollectionOptions *ebpf.CollectionOptions
-	BindLan           bool
-	BindWan           bool
 }
 
 func fullLoadBpfObjects(

control/control_plane.go

@@ -131,8 +131,6 @@ func NewControlPlane(
 		if err = fullLoadBpfObjects(log, bpf, &loadBpfOptions{
 			PinPath:           pinPath,
 			CollectionOptions: collectionOpts,
-			BindLan:           len(global.LanInterface) > 0,
-			BindWan:           len(global.WanInterface) > 0,
 		}); err != nil {
 			if log.Level == logrus.PanicLevel {
 				log.Panicln(err)