diff --git a/iflytop_xsync_protocol.h b/iflytop_xsync_protocol.h
index de34154..e9518cd 100644
--- a/iflytop_xsync_protocol.h
+++ b/iflytop_xsync_protocol.h
@@ -44,6 +44,16 @@ typedef enum {
   kxsync_packet_type_report  = 2,
 } xsync_protocol_packet_type_t;
 
+typedef enum {
+  kxs_ec_success                    = 0,
+  kxs_ec_overtime                   = 1,
+  kxs_ec_socket_fail                = 2,
+  kxs_ec_bind_fail                  = 3,
+  kxs_ec_send_fail                  = 4,
+  kxs_ec_receive_fail               = 5,
+  kxs_ec_setsockopt_rx_timeout_fail = 6,
+} xs_error_code_t;
+
 #pragma pack(1)
 
 typedef struct {