1 files changed, 1 insertions, 0 deletions
diff --git a/src/tun.go b/src/tun.go
index f529c54..d782bd5 100644
--- a/src/tun.go
+++ b/src/tun.go
@@ -9,6 +9,7 @@ const DefaultMTU = 1420
 type TUNDevice interface {
 	Read([]byte) (int, error)  // read a packet from the device (without any additional headers)
 	Write([]byte) (int, error) // writes a packet to the device (without any additional headers)
+	IsUp() (bool, error)       // is the interface up?
 	MTU() (int, error)         // returns the MTU of the device
 	Name() string              // returns the current name
 }