IPSEC_M_CTL
#define KEYSOCK_IN (IPSEC_M_CTL + 3)
#define KEYSOCK_OUT (IPSEC_M_CTL + 4)
#define KEYSOCK_OUT_ERR (IPSEC_M_CTL + 5)
#define KEYSOCK_HELLO (IPSEC_M_CTL + 6)
#define KEYSOCK_HELLO_ACK (IPSEC_M_CTL + 7)