diff --git a/shadowsocks/tcprelay.py b/shadowsocks/tcprelay.py
index cb478f4..314e96d 100644
--- a/shadowsocks/tcprelay.py
+++ b/shadowsocks/tcprelay.py
@@ -319,7 +319,7 @@ class TCPRelayHandler(object):
                         traceback.print_exc()
                     self.destroy()
 
-    def _handle_stage_addr(self, data):
+    def _handle_stage_addr(self, ogn_data, data):
         try:
             if self._is_local:
                 cmd = common.ord(data[1])
@@ -345,13 +345,18 @@ class TCPRelayHandler(object):
                     logging.error('unknown command %d', cmd)
                     self.destroy()
                     return
+
+            before_parse_data = data
             if FORCE_NEW_PROTOCOL and ord(data[0]) != 0x88:
+                logging.warn("TCP data %s decrypt %s" % (binascii.hexlify(ogn_data), binascii.hexlify(before_parse_data)))
                 raise Exception('can not parse header')
             data = pre_parse_header(data)
             if data is None:
+                logging.warn("TCP data %s decrypt %s" % (binascii.hexlify(ogn_data), binascii.hexlify(before_parse_data)))
                 raise Exception('can not parse header')
             header_result = parse_header(data)
             if header_result is None:
+                logging.warn("TCP data %s decrypt %s" % (binascii.hexlify(ogn_data), binascii.hexlify(before_parse_data)))
                 raise Exception('can not parse header')
             connecttype, remote_addr, remote_port, header_length = header_result
             logging.info('%s connecting %s:%d from %s:%d' %
@@ -497,6 +502,7 @@ class TCPRelayHandler(object):
         if not data:
             self.destroy()
             return
+        ogn_data = data
         self._update_activity(len(data))
         if not is_local:
             data = self._encryptor.decrypt(data)
@@ -517,7 +523,7 @@ class TCPRelayHandler(object):
             self._handle_stage_connecting(data)
         elif (is_local and self._stage == STAGE_ADDR) or \
                 (not is_local and self._stage == STAGE_INIT):
-            self._handle_stage_addr(data)
+            self._handle_stage_addr(ogn_data, data)
 
     def _on_remote_read(self, is_remote_sock):
         # handle all remote read events