import argparse import cPickle as pickle import os import platform import socket import SocketServer import threading import time from collections import OrderedDict from pydivert.windivert import WinDivert from pydivert.enum import Direction, Layer, Flag PROXY_API_PORT = 8085 class Resolver(object): def __init__(self): TransparentProxy.setup() self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) self.socket.connect(("127.0.0.1", PROXY_API_PORT)) self.wfile = self.socket.makefile('wb') self.rfile = self.socket.makefile('rb') self.lock = threading.Lock() def original_addr(self, csock): client = csock.getpeername()[:2] with self.lock: pickle.dump(client, self.wfile) self.wfile.flush() return pickle.load(self.rfile) class APIRequestHandler(SocketServer.StreamRequestHandler): """ TransparentProxy API: Returns the pickled server address, port tuple for each received pickled client address, port tuple. """ def handle(self): proxifier = self.server.proxifier while True: # print("API connection") client = pickle.load(self.rfile) # print("Received API Request: %s" % str(client)) server = proxifier.client_server_map[client] pickle.dump(server, self.wfile) self.wfile.flush() # print("API request handled") class APIServer(SocketServer.ThreadingMixIn, SocketServer.TCPServer): pass class TransparentProxy(object): """ Transparent Windows Proxy for mitmproxy based on WinDivert/PyDivert. Requires elevated (admin) privileges. Can be started separately by manually running the file. This module can be used to intercept and redirect all traffic that is forwarded by the user's machine. This does NOT include traffic sent from the machine itself, which cannot be accomplished by this approach for technical reasons (we cannot distinguish between requests made by the proxy or by regular applications. Altering the destination the proxy is seeing to some meta address does not work with TLS as the address doesn't match the signature.) How it works: (1) First, we intercept all packages that are forwarded by the OS (WinDivert's NETWORK_FORWARD layer) and whose destination port matches our filter (80 and 443 by default). For each intercepted package, we 1. Store the source -> destination mapping (address and port) 2. Remove the package from the network (by not reinjecting it). 3. Re-inject the package into the local network stack, but with the destination address changed to the proxy. (2) Next, the proxy receives the forwarded packet, but does not know the real destination yet (which we overwrote with the proxy's address). On Linux, we would now call getsockopt(SO_ORIGINAL_DST), but that unfortunately doesn't work on Windows. However, we still have the correct source information. As a workaround, we now access the forward module's API (see APIRequestHandler), submit the source information and get the actual destination back (which the forward module stored in (1.3)). (3) The proxy now establish the upstream connection as usual. (4) Finally, the proxy sends the response back to the client. To make it work, we need to change the packet's source address back to the original destination (using the mapping from (1.3)), to which the client believes he is talking to. """ def __init__(self, redirect_ports=(80, 443), proxy_addr=False, proxy_port=8080, api_host="localhost", api_port=PROXY_API_PORT, cache_size=65536): """ :param redirect_ports: if the destination port is in this tuple, the requests are redirected to the proxy. :param proxy_addr: IP address of the proxy (IP within a network, 127.0.0.1 does not work). By default, this is detected automatically. :param proxy_port: Port the proxy is listenting on. :param api_host: Host the forward module API is listening on. :param api_port: Port the forward module API is listening on. :param cache_size: Maximum number of connection tuples that are stored. Only relevant in very high load scenarios. """ if not proxy_addr: # Auto-Detect local IP. # https://stackoverflow.com/questions/166506/finding-local-ip-addresses-using-pythons-stdlib s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) s.connect(("8.8.8.8", 80)) proxy_addr = s.getsockname()[0] s.close() self.client_server_map = OrderedDict() self.proxy_addr, self.proxy_port = proxy_addr, proxy_port self.connection_cache_size = cache_size self.api_server = APIServer((api_host, api_port), APIRequestHandler) self.api_server.proxifier = self self.api_server_thread = threading.Thread(target=self.api_server.serve_forever) self.api_server_thread.daemon = True arch = "amd64" if platform.architecture()[0] == "64bit" else "x86" self.driver = WinDivert(os.path.join(os.path.dirname(__file__), "..", "contrib", "windivert", arch, "WinDivert.dll")) self.driver.register() filter_forward = " or ".join( ("tcp.DstPort == %d" % p) for p in redirect_ports) self.handle_forward = self.driver.open_handle(filter=filter_forward, layer=Layer.NETWORK_FORWARD) self.forward_thread = threading.Thread(target=self.redirect) self.forward_thread.daemon = True filter_local = "outbound and tcp.SrcPort == %d" % proxy_port self.handle_local = self.driver.open_handle(filter=filter_local, layer=Layer.NETWORK) self.local_thread = threading.Thread(target=self.adjust_source) self.local_thread.daemon = True self.handle_icmp = self.driver.open_handle(filter="icmp", layer=Layer.NETWORK, flags=Flag.DROP) @classmethod def setup(cls): # TODO: Make sure that server can be killed cleanly. That's a bit difficult as we don't have access to # controller.should_exit when this is called. s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server_unavailable = s.connect_ex(("127.0.0.1", PROXY_API_PORT)) if server_unavailable: proxifier = TransparentProxy() proxifier.start() def start(self): self.api_server_thread.start() self.local_thread.start() self.forward_thread.start() def shutdown(self): self.handle_forward.close() self.handle_local.close() self.handle_icmp.close() self.api_server.shutdown() def recv(self, handle): """ Convenience function that receives a packet from the passed handler and handles error codes. If the process has been shut down, (None, None) is returned. """ try: raw_packet, metadata = handle.recv() return self.driver.parse_packet(raw_packet), metadata except WindowsError, e: if e.winerror == 995: return None, None else: raise def redirect(self): """ Redirect packages to the proxy """ while True: packet, metadata = self.recv(self.handle_forward) if not packet: return # print(" * Redirect client -> server to proxy") # print("%s:%s -> %s:%s" % (packet.src_addr, packet.src_port, packet.dst_addr, packet.dst_port)) client = (packet.src_addr, packet.src_port) server = (packet.dst_addr, packet.dst_port) if client in self.client_server_map: del self.client_server_map[client] while len(self.client_server_map) > self.connection_cache_size: self.client_server_map.popitem(False) self.client_server_map[client] = server packet.dst_addr, packet.dst_port = self.proxy_addr, self.proxy_port metadata.direction = Direction.INBOUND packet = self.driver.update_packet_checksums(packet) self.handle_local.send((packet.raw, metadata)) def adjust_source(self): """ Spoof source address of packets send from the proxy to the client """ while True: packet, metadata = self.recv(self.handle_local) if not packet: return # If the proxy responds to the client, let the client believe the target server sent the packets. # print(" * Adjust proxy -> client") client = (packet.dst_addr, packet.dst_port) server = self.client_server_map[client] packet.src_addr, packet.src_port = server packet = self.driver.update_packet_checksums(packet) self.handle_local.send((packet.raw, metadata)) def icmp_block(self): """ Block all ICMP requests (which are sent on Windows by default). In layman's terms: If we don't do this, our proxy machine tells the client that it can directly connect to the real gateway if they are on the same network. """ while True: packet, metadata = self.recv(self.handle_icmp) if not packet: return # no nothing with the received packet, do not reinject it. if __name__ == "__main__": parser = argparse.ArgumentParser(description="Windows Transparent Proxy") parser.add_argument("--redirect-ports", nargs="+", type=int, default=[80, 443], metavar="80", help="ports that should be forwarded to the proxy") parser.add_argument("--proxy-addr", default=False, help="proxy server address") parser.add_argument("--proxy-port", type=int, default=8080, help="proxy server port") parser.add_argument("--api-host", default="localhost", help="API hostname to bind to") parser.add_argument("--api-port", type=int, default=PROXY_API_PORT, help="API port") parser.add_argument("--cache-size", type=int, default=65536, help="maximum connection cache size") options = parser.parse_args() proxifier = TransparentProxy(**vars(options)) proxifier.start() print(" * Transparent proxy active.") try: while True: time.sleep(1) except KeyboardInterrupt: print(" * Shutting down...") proxifier.shutdown() print(" * Shut down.")