for GPRS tunneling protocol, new in linux commit 459aa660eb1d8ce67080da1983bb81d716aa5a69
@@ -28,6 +28,8 @@ struct udphdr {
#define UDP_ENCAP_ESPINUDP_NON_IKE 1
#define UDP_ENCAP_ESPINUDP 2
#define UDP_ENCAP_L2TPINUDP 3
+#define UDP_ENCAP_GTP0 4
+#define UDP_ENCAP_GTP1U 5
#define SOL_UDP 17