diff --git a/README.md b/README.md
index 1fed484..bd33fa7 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 shadowsocks
 ===========
 
-Current version: 1.3.7 [![Build Status](https://travis-ci.org/clowwindy/shadowsocks.png?branch=master)](https://travis-ci.org/clowwindy/shadowsocks)
+Current version: 1.4.0 [![Build Status](https://travis-ci.org/clowwindy/shadowsocks.png?branch=master)](https://travis-ci.org/clowwindy/shadowsocks)
 
 shadowsocks is a lightweight tunnel proxy which can help you get through firewalls.
 
diff --git a/setup.py b/setup.py
index 86d7a0c..5ec5185 100644
--- a/setup.py
+++ b/setup.py
@@ -1,23 +1,22 @@
-from setuptools import setup 
+from setuptools import setup
 
 
 with open('README.rst') as f:
     long_description = f.read()
 
 setup(
-    name = "shadowsocks",
-    version = "1.3.7",
-    license = 'MIT',
-    description = "a lightweight tunnel proxy",
-    author = 'clowwindy',
-    author_email = 'clowwindy42@gmail.com',
-    url = 'https://github.com/clowwindy/shadowsocks',
-    packages = ['shadowsocks'],
+    name="shadowsocks",
+    version="1.4.0",
+    license='MIT',
+    description="a lightweight tunnel proxy",
+    author='clowwindy',
+    author_email='clowwindy42@gmail.com',
+    url='https://github.com/clowwindy/shadowsocks',
+    packages=['shadowsocks'],
     package_data={
         'shadowsocks': ['README.rst', 'LICENSE', 'config.json']
     },
-    install_requires = ['setuptools',
-                        ],
+    install_requires=['setuptools'],
     entry_points="""
     [console_scripts]
     sslocal = shadowsocks.local:main
@@ -29,6 +28,6 @@ setup(
         'Programming Language :: Python :: 2.6',
         'Programming Language :: Python :: 2.7',
         'Topic :: Internet :: Proxy Servers',
-        ],
+    ],
     long_description=long_description,
 )
diff --git a/shadowsocks/event.py b/shadowsocks/event.py
new file mode 100644
index 0000000..737d039
--- /dev/null
+++ b/shadowsocks/event.py
@@ -0,0 +1,147 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2014 clowwindy
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+# from ssloop
+# https://github.com/clowwindy/ssloop
+
+
+import select
+from collections import defaultdict
+
+
+MODE_NULL = 0x00
+MODE_IN = 0x01
+MODE_OUT = 0x04
+MODE_ERR = 0x08
+MODE_HUP = 0x10
+MODE_NVAL = 0x20
+
+
+class EpollLoop(object):
+
+    def __init__(self):
+        self._epoll = select.epoll()
+
+    def poll(self, timeout):
+        return self._epoll.poll(timeout)
+
+    def add_fd(self, fd, mode):
+        self._epoll.register(fd, mode)
+
+    def remove_fd(self, fd):
+        self._epoll.unregister(fd)
+
+    def modify_fd(self, fd, mode):
+        self._epoll.modify(fd, mode)
+
+
+class KqueueLoop(object):
+
+    MAX_EVENTS = 1024
+
+    def __init__(self):
+        self._kqueue = select.kqueue()
+        self._fds = {}
+
+    def _control(self, fd, mode, flags):
+        events = []
+        if mode & MODE_IN:
+            events.append(select.kevent(fd, select.KQ_FILTER_READ, flags))
+        if mode & MODE_OUT:
+            events.append(select.kevent(fd, select.KQ_FILTER_WRITE, flags))
+        for e in events:
+            self._kqueue.control([e], 0)
+
+    def poll(self, timeout):
+        if timeout < 0:
+            timeout = None  # kqueue behaviour
+        events = self._kqueue.control(None, KqueueLoop.MAX_EVENTS, timeout)
+        results = defaultdict(lambda: MODE_NULL)
+        for e in events:
+            fd = e.ident
+            if e.filter == select.KQ_FILTER_READ:
+                results[fd] |= MODE_IN
+            elif e.filter == select.KQ_FILTER_WRITE:
+                results[fd] |= MODE_OUT
+        return results.iteritems()
+
+    def add_fd(self, fd, mode):
+        self._fds[fd] = mode
+        self._control(fd, mode, select.KQ_EV_ADD)
+
+    def remove_fd(self, fd):
+        self._control(fd, self._fds[fd], select.KQ_EV_DELETE)
+        del self._fds[fd]
+
+    def modify_fd(self, fd, mode):
+        self.remove_fd(fd)
+        self.add_fd(fd, mode)
+
+
+class SelectLoop(object):
+
+    def __init__(self):
+        self._r_list = set()
+        self._w_list = set()
+        self._x_list = set()
+
+    def poll(self, timeout):
+        r, w, x = select.select(self._r_list, self._w_list, self._x_list,
+                                timeout)
+        results = defaultdict(lambda: MODE_NULL)
+        for p in [(r, MODE_IN), (w, MODE_OUT), (x, MODE_ERR)]:
+            for fd in p[0]:
+                results[fd] |= p[1]
+        return results.items()
+
+    def add_fd(self, fd, mode):
+        if mode & MODE_IN:
+            self._r_list.add(fd)
+        if mode & MODE_OUT:
+            self._w_list.add(fd)
+        if mode & MODE_ERR:
+            self._x_list.add(fd)
+
+    def remove_fd(self, fd):
+        if fd in self._r_list:
+            self._r_list.remove(fd)
+        if fd in self._w_list:
+            self._w_list.remove(fd)
+        if fd in self._x_list:
+            self._x_list.remove(fd)
+
+    def modify_fd(self, fd, mode):
+        self.remove_fd(fd)
+        self.add_fd(fd, mode)
+
+
+EventLoop = None
+
+if hasattr(select, 'epoll'):
+    EventLoop = EpollLoop
+elif hasattr(select, 'kqueue'):
+    EventLoop = KqueueLoop
+elif hasattr(select, 'select'):
+    EventLoop = SelectLoop
+else:
+    raise Exception('can not find any available functions in select package')
diff --git a/shadowsocks/local.py b/shadowsocks/local.py
index 11394c9..0453ea2 100755
--- a/shadowsocks/local.py
+++ b/shadowsocks/local.py
@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+# -*- coding: utf-8 -*-
 
 # Copyright (c) 2014 clowwindy
 #
diff --git a/shadowsocks/server.py b/shadowsocks/server.py
index ba161fd..6b2c887 100755
--- a/shadowsocks/server.py
+++ b/shadowsocks/server.py
@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+# -*- coding: utf-8 -*-
 
 # Copyright (c) 2014 clowwindy
 #
@@ -27,6 +28,9 @@ if sys.version_info < (2, 6):
 else:
     import json
 
+# do this before monkey patch
+import udprelay
+
 try:
     import gevent
     import gevent.monkey
@@ -40,7 +44,6 @@ import select
 import threading
 import SocketServer
 import struct
-import os
 import logging
 import getopt
 import encrypt
@@ -205,6 +208,7 @@ def main():
         server.key, server.method, server.timeout = key, METHOD, int(TIMEOUT)
         logging.info("starting server at %s:%d" % tuple(server.server_address[:2]))
         threading.Thread(target=server.serve_forever).start()
+        
 
 if __name__ == '__main__':
     try:
diff --git a/shadowsocks/udprelay.py b/shadowsocks/udprelay.py
new file mode 100644
index 0000000..841c035
--- /dev/null
+++ b/shadowsocks/udprelay.py
@@ -0,0 +1,117 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2014 clowwindy
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+# SOCKS5 UDP Request
+# +----+------+------+----------+----------+----------+
+# |RSV | FRAG | ATYP | DST.ADDR | DST.PORT |   DATA   |
+# +----+------+------+----------+----------+----------+
+# | 2  |  1   |  1   | Variable |    2     | Variable |
+# +----+------+------+----------+----------+----------+
+
+# SOCKS5 UDP Response
+# +----+------+------+----------+----------+----------+
+# |RSV | FRAG | ATYP | DST.ADDR | DST.PORT |   DATA   |
+# +----+------+------+----------+----------+----------+
+# | 2  |  1   |  1   | Variable |    2     | Variable |
+# +----+------+------+----------+----------+----------+
+
+# shadowsocks UDP Request (before encrypted)
+# +------+----------+----------+----------+
+# | ATYP | DST.ADDR | DST.PORT |   DATA   |
+# +------+----------+----------+----------+
+# |  1   | Variable |    2     | Variable |
+# +------+----------+----------+----------+
+
+# shadowsocks UDP Response (before encrypted)
+# +------+----------+----------+----------+
+# | ATYP | DST.ADDR | DST.PORT |   DATA   |
+# +------+----------+----------+----------+
+# |  1   | Variable |    2     | Variable |
+# +------+----------+----------+----------+
+
+# shadowsocks UDP Request and Response (after encrypted)
+# +-------+--------------+
+# |   IV  |    PAYLOAD   |
+# +-------+--------------+
+# | Fixed |   Variable   |
+# +-------+--------------+
+
+# HOW TO NAME THINGS
+# ------------------
+# `dest`    means destination server, which is from DST fields in the SOCKS5
+#           request
+# `local`   means local server of shadowsocks
+# `remote`  means remote server of shadowsocks
+# `client`  means UDP clients that connects to other servers
+# `server`  means the UDP server that handle user requests
+
+
+import threading
+import socket
+import event
+
+
+class UDPRelay(object):
+    def __init__(self, listen_addr='127.0.0.1', listen_port=1080,
+                 remote_addr='127.0.0.1', remote_port=8387, password=None,
+                 method='table', timeout=300, is_local=True):
+        self._listen_addr = listen_addr
+        self._listen_port = listen_port
+        self._remote_addr = remote_addr
+        self._remote_port = remote_port
+        self._password = password
+        self._method = method
+        self._timeout = timeout
+        self._is_local = is_local
+        self._eventloop = event.EventLoop()
+
+    def _handle_server(self, addr, sock, data):
+        # TODO
+        pass
+
+    def _handle_client(self, addr, sock, data):
+        # TODO
+        pass
+
+    def _run(self):
+        eventloop = self._eventloop
+        server_socket = self._server_socket
+        eventloop.add_fd(server_socket, event.MODE_IN)
+        is_local = self._is_local
+        while True:
+            r = eventloop.poll()
+            # TODO
+
+    def start(self):
+        addrs = socket.getaddrinfo(self._listen_addr, self._listen_port, 0,
+                                   socket.SOCK_DGRAM, socket.SOL_UDP)
+        if len(addrs) == 0:
+            raise Exception("can't get addrinfo for %s:%d" %
+                            (self._listen_addr, self._listen_port))
+        af, socktype, proto, canonname, sa = addrs[0]
+        server_socket = socket.socket(af, socktype, proto)
+        server_socket.bind((self._listen_addr, self._listen_port))
+        server_socket.setblocking(False)
+        self._server_socket = server_socket
+
+        threading.Thread(target=self._run).start()