diff --git a/shadowsocks/tcprelay.py b/shadowsocks/tcprelay.py
index 1387ac7..cc49d67 100644
--- a/shadowsocks/tcprelay.py
+++ b/shadowsocks/tcprelay.py
@@ -328,6 +328,7 @@ class TCPRelayHandler(object):
             if self._is_local is False:
                 # spec https://shadowsocks.org/en/spec/one-time-auth.html
                 if self._ota_enable or addrtype & ADDRTYPE_AUTH:
+                    self._ota_enable = True
                     if len(data) < header_length + ONETIMEAUTH_BYTES:
                         logging.warn('one time auth header is too short')
                         return None
diff --git a/shadowsocks/udprelay.py b/shadowsocks/udprelay.py
index 6bf6ce6..849f611 100644
--- a/shadowsocks/udprelay.py
+++ b/shadowsocks/udprelay.py
@@ -184,6 +184,7 @@ class UDPRelay(object):
             server_addr, server_port = dest_addr, dest_port
             # spec https://shadowsocks.org/en/spec/one-time-auth.html
             if self._one_time_auth_enable or addrtype & ADDRTYPE_AUTH:
+                self._one_time_auth_enable = True
                 if len(data) < header_length + ONETIMEAUTH_BYTES:
                     logging.warn('UDP one time auth header is too short')
                     return