diff --git a/mujson_mgr.py b/mujson_mgr.py
index cda7ea7..d986ca5 100644
--- a/mujson_mgr.py
+++ b/mujson_mgr.py
@@ -147,6 +147,7 @@ Options:
   -O PROTOCOL            protocol plugin, default: auth_sha1_v2_compatible
   -o OBFS                obfs plugin, default: tls1.2_ticket_auth_compatible
   -t TRANSFER            max transfer for G bytes, default: 1048576, can be float point number
+  -f FORBID              set forbidden ports. Example (ban 1~79 and 81~100): -f "1-79,81-100"
 
 General options:
   -h, --help             show this help message and exit
diff --git a/shadowsocks/tcprelay.py b/shadowsocks/tcprelay.py
index 859e92c..1349f62 100644
--- a/shadowsocks/tcprelay.py
+++ b/shadowsocks/tcprelay.py
@@ -994,14 +994,11 @@ class TCPRelay(object):
                 self._stat_counter[self._listen_port] = {}
             newval = self._stat_counter[self._listen_port].get(local_addr, 0) + val
             logging.debug('port %d addr %s connections %d' % (self._listen_port, local_addr, newval))
+            self._stat_counter[self._listen_port][local_addr] = newval
+            self.update_stat(self._listen_port, self._stat_counter[self._listen_port], val)
             if newval <= 0:
                 if local_addr in self._stat_counter[self._listen_port]:
                     del self._stat_counter[self._listen_port][local_addr]
-                if len(self._stat_counter[self._listen_port]) == 0:
-                    del self._stat_counter[self._listen_port]
-            else:
-                self._stat_counter[self._listen_port][local_addr] = newval
-                self.update_stat(self._listen_port, self._stat_counter[self._listen_port], val)
 
             newval = self._stat_counter.get(0, 0) + val
             self._stat_counter[0] = newval