add tun/tap

pkg/internal/util/tun/config.go

@@ -0,0 +1,19 @@
+package tun
+
+import "net"
+
+// Route is an IP routing entry
+type Route struct {
+	Net     net.IPNet
+	Gateway net.IP
+}
+
+type Config struct {
+	Name string
+	Net  string
+	// peer addr of point-to-point on MacOS
+	Peer    string
+	MTU     int
+	Gateway string
+	Routes  []Route
+}