内网穿透--TCP打洞
原理
准备一台内网机器（Slaver），一台外网机器（Master）
Master一边监听Slaver的连接，一边监听来自外网客户端的连接
Master将外网客户端的连接进行解析并转发给Slaver，实现外网访问内网（内网穿透）
代码实现
Master.py
Slaver.py
Github地址
Last updated
准备一台内网机器（Slaver），一台外网机器（Master）
Master一边监听Slaver的连接，一边监听来自外网客户端的连接
Master将外网客户端的连接进行解析并转发给Slaver，实现外网访问内网（内网穿透）
Last updated
#!/usr/bin/env python3
# coding=utf-8
from common_func import *
import queue
import atexit
_listening_sockets = [] # for close at exit
__author__ = "Aploium <i@z.codes>"
__website__ = "https://github.com/aploium/shootback"
@atexit.register
def close_listening_socket_at_exit():
log.info("exiting...")
for s in _listening_sockets:
log.info("closing: {}".format(s))
try_close(s)
def try_bind_port(sock, addr):
while True:
try:
sock.bind(addr)
except Exception as e:
log.error(("unable to bind {}, {}. If this port was used by the recently-closed shootback itself\n"
"then don't worry, it would be available in several seconds\n"
"we'll keep trying....").format(addr, e))
log.debug(traceback.format_exc())
time.sleep(3)
else:
break
class Master:
def __init__(self, customer_listen_addr, communicate_addr=None,
slaver_pool=None, working_pool=None):
"""
:param customer_listen_addr: equals to the -c/--customer param
:param communicate_addr: equals to the -m/--master param
"""
self.thread_pool = {}
self.thread_pool["spare_slaver"] = {}
self.thread_pool["working_slaver"] = {}
self.working_pool = working_pool or {}
self.socket_bridge = SocketBridge()
# a queue for customers who have connected to us,
# but not assigned a slaver yet
self.pending_customers = queue.Queue()
self.communicate_addr = communicate_addr
_fmt_communicate_addr = fmt_addr(self.communicate_addr)
if slaver_pool:
# 若使用外部slaver_pool, 就不再初始化listen
# 这是以后待添加的功能
self.external_slaver = True
self.thread_pool["listen_slaver"] = None
else:
# 自己listen来获取slaver
self.external_slaver = False
self.slaver_pool = collections.deque()
# prepare Thread obj, not activated yet
self.thread_pool["listen_slaver"] = threading.Thread(
target=self._listen_slaver,
name="listen_slaver-{}".format(_fmt_communicate_addr),
daemon=True,
)
# prepare Thread obj, not activated yet
self.customer_listen_addr = customer_listen_addr
self.thread_pool["listen_customer"] = threading.Thread(
target=self._listen_customer,
name="listen_customer-{}".format(_fmt_communicate_addr),
daemon=True,
)
# prepare Thread obj, not activated yet
self.thread_pool["heart_beat_daemon"] = threading.Thread(
target=self._heart_beat_daemon,
name="heart_beat_daemon-{}".format(_fmt_communicate_addr),
daemon=True,
)
# prepare assign_slaver_daemon
self.thread_pool["assign_slaver_daemon"] = threading.Thread(
target=self._assign_slaver_daemon,
name="assign_slaver_daemon-{}".format(_fmt_communicate_addr),
daemon=True,
)
def serve_forever(self):
if not self.external_slaver:
self.thread_pool["listen_slaver"].start()
self.thread_pool["heart_beat_daemon"].start()
self.thread_pool["listen_customer"].start()
self.thread_pool["assign_slaver_daemon"].start()
self.thread_pool["socket_bridge"] = self.socket_bridge.start_as_daemon()
while True:
time.sleep(10)
def _transfer_complete(self, addr_customer):
"""a callback for SocketBridge, do some cleanup jobs"""
log.info("customer complete: {}".format(addr_customer))
del self.working_pool[addr_customer]
def _serve_customer(self, conn_customer, conn_slaver):
"""put customer and slaver sockets into SocketBridge, let them exchange data"""
self.socket_bridge.add_conn_pair(
conn_customer, conn_slaver,
functools.partial( # it's a callback
# 这个回调用来在传输完成后删除工作池中对应记录
self._transfer_complete,
conn_customer.getpeername()
)
)
@staticmethod
def _send_heartbeat(conn_slaver):
"""send and verify heartbeat pkg"""
conn_slaver.send(CtrlPkg.pbuild_heart_beat().raw)
pkg, verify = CtrlPkg.recv(
conn_slaver, expect_ptype=CtrlPkg.PTYPE_HEART_BEAT) # type: CtrlPkg,bool
if not verify:
return False
if pkg.prgm_ver < 0x000B:
# shootback before 2.2.5-r10 use two-way heartbeat
# so there is no third pkg to send
pass
else:
# newer version use TCP-like 3-way heartbeat
# the older 2-way heartbeat can't only ensure the
# master --> slaver pathway is OK, but the reverse
# communicate may down. So we need a TCP-like 3-way
# heartbeat
conn_slaver.send(CtrlPkg.pbuild_heart_beat().raw)
return verify
def _heart_beat_daemon(self):
"""
每次取出slaver队列头部的一个, 测试心跳, 并把它放回尾部.
slaver若超过 SPARE_SLAVER_TTL 秒未收到心跳, 则会自动重连
所以睡眠间隔(delay)满足 delay * slaver总数 < TTL
使得一轮循环的时间小于TTL,
保证每个slaver都在过期前能被心跳保活
"""
default_delay = 5 + SPARE_SLAVER_TTL // 12
delay = default_delay
log.info("heart beat daemon start, delay: {}s".format(delay))
while True:
time.sleep(delay)
# log.debug("heart_beat_daemon: hello! im weak")
# ---------------------- preparation -----------------------
slaver_count = len(self.slaver_pool)
if not slaver_count:
log.warning("heart_beat_daemon: sorry, no slaver available, keep sleeping")
# restore default delay if there is no slaver
delay = default_delay
continue
else:
# notice this `slaver_count*2 + 1`
# slaver will expire and re-connect if didn't receive
# heartbeat pkg after SPARE_SLAVER_TTL seconds.
# set delay to be short enough to let every slaver receive heartbeat
# before expire
delay = 1 + SPARE_SLAVER_TTL // max(slaver_count * 2 + 1, 12)
# pop the oldest slaver
# heartbeat it and then put it to the end of queue
slaver = self.slaver_pool.popleft()
addr_slaver = slaver["addr_slaver"]
# ------------------ real heartbeat begin --------------------
start_time = time.perf_counter()
try:
hb_result = self._send_heartbeat(slaver["conn_slaver"])
except Exception as e:
log.warning("error during heartbeat to {}: {}".format(
fmt_addr(addr_slaver), e))
log.debug(traceback.format_exc())
hb_result = False
finally:
time_used = round((time.perf_counter() - start_time) * 1000.0, 2)
# ------------------ real heartbeat end ----------------------
if not hb_result:
log.warning("heart beat failed: {}, time: {}ms".format(
fmt_addr(addr_slaver), time_used))
try_close(slaver["conn_slaver"])
del slaver["conn_slaver"]
# if heartbeat failed, start the next heartbeat immediately
# because in most cases, all 5 slaver connection will
# fall and re-connect in the same time
delay = 0
else:
log.debug("heartbeat success: {}, time: {}ms".format(
fmt_addr(addr_slaver), time_used))
self.slaver_pool.append(slaver)
@staticmethod
def _handshake(conn_slaver):
"""
handshake before real data transfer
it ensures:
1. client is alive and ready for transmission
2. client is shootback_slaver, not mistakenly connected other program
3. verify the SECRET_KEY
4. tell slaver it's time to connect target
handshake procedure:
1. master hello --> slaver
2. slaver verify master's hello
3. slaver hello --> master
4. (immediately after 3) slaver connect to target
4. master verify slaver
5. enter real data transfer
"""
conn_slaver.send(CtrlPkg.pbuild_hs_m2s().raw)
buff = select_recv(conn_slaver, CtrlPkg.PACKAGE_SIZE, 2)
if buff is None:
return False
pkg, verify = CtrlPkg.decode_verify(buff, CtrlPkg.PTYPE_HS_S2M) # type: CtrlPkg,bool
log.debug("CtrlPkg from slaver {}: {}".format(conn_slaver.getpeername(), pkg))
return verify
def _get_an_active_slaver(self):
"""get and activate an slaver for data transfer"""
try_count = 100
while True:
try:
dict_slaver = self.slaver_pool.popleft()
except:
if try_count:
time.sleep(0.02)
try_count -= 1
if try_count % 10 == 0:
log.error("!!NO SLAVER AVAILABLE!! trying {}".format(try_count))
continue
return None
conn_slaver = dict_slaver["conn_slaver"]
try:
hs = self._handshake(conn_slaver)
except Exception as e:
log.warning("Handshake failed: {}".format(e))
log.debug(traceback.format_exc())
hs = False
if hs:
return conn_slaver
else:
log.warning("slaver handshake failed: {}".format(dict_slaver["addr_slaver"]))
try_close(conn_slaver)
time.sleep(0.02)
def _assign_slaver_daemon(self):
"""assign slaver for customer"""
while True:
# get a newly connected customer
conn_customer, addr_customer = self.pending_customers.get()
conn_slaver = self._get_an_active_slaver()
if conn_slaver is None:
log.warning("Closing customer[{}] because no available slaver found".format(
addr_customer))
try_close(conn_customer)
continue
else:
log.debug("Using slaver: {} for {}".format(conn_slaver.getpeername(), addr_customer))
self.working_pool[addr_customer] = {
"addr_customer": addr_customer,
"conn_customer": conn_customer,
"conn_slaver": conn_slaver,
}
try:
self._serve_customer(conn_customer, conn_slaver)
except:
try:
try_close(conn_customer)
except:
pass
continue
def _listen_slaver(self):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try_bind_port(sock, self.communicate_addr)
sock.listen(10)
_listening_sockets.append(sock)
log.info("Listening for slavers: {}".format(
fmt_addr(self.communicate_addr)))
while True:
conn, addr = sock.accept()
self.slaver_pool.append({
"addr_slaver": addr,
"conn_slaver": conn,
})
log.info("Got slaver {} Total: {}".format(
fmt_addr(addr), len(self.slaver_pool)
))
def _listen_customer(self):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try_bind_port(sock, self.customer_listen_addr)
sock.listen(20)
_listening_sockets.append(sock)
log.info("Listening for customers: {}".format(
fmt_addr(self.customer_listen_addr)))
while True:
conn_customer, addr_customer = sock.accept()
log.info("Serving customer: {} Total customers: {}".format(
addr_customer, self.pending_customers.qsize() + 1
))
# just put it into the queue,
# let _assign_slaver_daemon() do the else
# don't block this loop
self.pending_customers.put((conn_customer, addr_customer))
def run_master(communicate_addr, customer_listen_addr):
log.info("shootback {} running as master".format(version_info()))
log.info("author: {} site: {}".format(__author__, __website__))
log.info("slaver from: {} customer from: {}".format(
fmt_addr(communicate_addr), fmt_addr(customer_listen_addr)))
Master(customer_listen_addr, communicate_addr).serve_forever()
def argparse_master():
import argparse
parser = argparse.ArgumentParser(
description="""shootback (master) {ver}
A fast and reliable reverse TCP tunnel. (this is master)
Help access local-network service from Internet.
https://github.com/aploium/shootback""".format(ver=version_info()),
epilog="""
Example1:
tunnel local ssh to public internet, assume master's ip is 1.2.3.4
Master(this pc): master.py -m 0.0.0.0:10000 -c 0.0.0.0:10022
Slaver(another private pc): slaver.py -m 1.2.3.4:10000 -t 127.0.0.1:22
Customer(any internet user): ssh 1.2.3.4 -p 10022
the actual traffic is: customer <--> master(1.2.3.4 this pc) <--> slaver(private network) <--> ssh(private network)
Example2:
Tunneling for www.example.com
Master(this pc): master.py -m 127.0.0.1:10000 -c 127.0.0.1:10080
Slaver(this pc): slaver.py -m 127.0.0.1:10000 -t example.com:80
Customer(this pc): curl -v -H "host: example.com" 127.0.0.1:10080
Tips: ANY service using TCP is shootback-able. HTTP/FTP/Proxy/SSH/VNC/...
""",
formatter_class=argparse.RawDescriptionHelpFormatter
)
parser.add_argument("-m", "--master", required=True,
metavar="host:port",
help="listening for slavers, usually an Public-Internet-IP. Slaver comes in here eg: 2.3.3.3:10000")
parser.add_argument("-c", "--customer", required=True,
metavar="host:port",
help="listening for customers, 3rd party program connects here eg: 10.1.2.3:10022")
parser.add_argument("-k", "--secretkey", default="shootback",
help="secretkey to identity master and slaver, should be set to the same value in both side")
parser.add_argument("-v", "--verbose", action="count", default=0,
help="verbose output")
parser.add_argument("-q", "--quiet", action="count", default=0,
help="quiet output, only display warning and errors, use two to disable output")
parser.add_argument("-V", "--version", action="version", version="shootback {}-master".format(version_info()))
parser.add_argument("--ttl", default=300, type=int, dest="SPARE_SLAVER_TTL",
help="standing-by slaver's TTL, default is 300. "
"In master side, this value affects heart-beat frequency. "
"Default value is optimized for most cases")
return parser.parse_args()
def main_master():
global SPARE_SLAVER_TTL
global SECRET_KEY
args = argparse_master()
if args.verbose and args.quiet:
print("-v and -q should not appear together")
exit(1)
communicate_addr = split_host(args.master)
customer_listen_addr = split_host(args.customer)
SECRET_KEY = args.secretkey
CtrlPkg.recalc_crc32()
SPARE_SLAVER_TTL = args.SPARE_SLAVER_TTL
if args.quiet < 2:
if args.verbose:
level = logging.DEBUG
elif args.quiet:
level = logging.WARNING
else:
level = logging.INFO
configure_logging(level)
run_master(communicate_addr, customer_listen_addr)
if __name__ == '__main__':
main_master()#!/usr/bin/env python
# coding=utf-8
from __future__ import print_function, unicode_literals, division, absolute_import
from common_func import *
__author__ = "Aploium <i@z.codes>"
__website__ = "https://github.com/aploium/shootback"
class Slaver:
"""
slaver socket阶段
连接master->等待->心跳(重复)--->握手-->正式传输数据->退出
"""
def __init__(self, communicate_addr, target_addr, max_spare_count=5):
self.communicate_addr = communicate_addr
self.target_addr = target_addr
self.max_spare_count = max_spare_count
self.spare_slaver_pool = {}
self.working_pool = {}
self.socket_bridge = SocketBridge()
def _connect_master(self):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(self.communicate_addr)
self.spare_slaver_pool[sock.getsockname()] = {
"conn_slaver": sock,
}
return sock
def _connect_target(self):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(self.target_addr)
log.debug("connected to target[{}] at: {}".format(
sock.getpeername(),
sock.getsockname(),
))
return sock
def _response_heartbeat(self, conn_slaver, hb_from_master):
# assert isinstance(hb_from_master, CtrlPkg)
# assert isinstance(conn_slaver, socket.SocketType)
if hb_from_master.prgm_ver < 0x000B:
# shootback before 2.2.5-r10 use two-way heartbeat
# so just send a heart_beat pkg back
conn_slaver.send(CtrlPkg.pbuild_heart_beat().raw)
return True
else:
# newer version use TCP-like 3-way heartbeat
# the older 2-way heartbeat can't only ensure the
# master --> slaver pathway is OK, but the reverse
# communicate may down. So we need a TCP-like 3-way
# heartbeat
conn_slaver.send(CtrlPkg.pbuild_heart_beat().raw)
pkg, verify = CtrlPkg.recv(
conn_slaver,
expect_ptype=CtrlPkg.PTYPE_HEART_BEAT) # type: CtrlPkg,bool
if verify:
log.debug("heartbeat success {}".format(
fmt_addr(conn_slaver.getsockname())))
return True
else:
log.warning(
"received a wrong pkg[{}] during heartbeat, {}".format(
pkg, conn_slaver.getsockname()
))
return False
def _stage_ctrlpkg(self, conn_slaver):
"""
handling CtrlPkg until handshake
well, there is only one CtrlPkg: heartbeat, yet
it ensures:
1. network is ok, master is alive
2. master is shootback_master, not bad guy
3. verify the SECRET_KEY
4. tell slaver it's time to connect target
handshake procedure:
1. master hello --> slaver
2. slaver verify master's hello
3. slaver hello --> master
4. (immediately after 3) slaver connect to target
4. master verify slaver
5. enter real data transfer
"""
while True: # 可能会有一段时间的心跳包
# recv master --> slaver
# timeout is set to `SPARE_SLAVER_TTL`
# which means if not receive pkg from master in SPARE_SLAVER_TTL seconds,
# this connection would expire and re-connect
pkg, verify = CtrlPkg.recv(conn_slaver, SPARE_SLAVER_TTL) # type: CtrlPkg,bool
if not verify:
return False
log.debug("CtrlPkg from {}: {}".format(conn_slaver.getpeername(), pkg))
if pkg.pkg_type == CtrlPkg.PTYPE_HEART_BEAT:
# if the pkg is heartbeat pkg, enter handshake procedure
if not self._response_heartbeat(conn_slaver, pkg):
return False
elif pkg.pkg_type == CtrlPkg.PTYPE_HS_M2S:
# 拿到了开始传输的握手包, 进入工作阶段
break
# send slaver hello --> master
conn_slaver.send(CtrlPkg.pbuild_hs_s2m().raw)
return True
def _transfer_complete(self, addr_slaver):
"""a callback for SocketBridge, do some cleanup jobs"""
del self.working_pool[addr_slaver]
log.info("slaver complete: {}".format(addr_slaver))
def _slaver_working(self, conn_slaver):
addr_slaver = conn_slaver.getsockname()
addr_master = conn_slaver.getpeername()
# --------- handling CtrlPkg until handshake -------------
try:
hs = self._stage_ctrlpkg(conn_slaver)
except Exception as e:
log.warning("slaver{} waiting handshake failed {}".format(
fmt_addr(addr_slaver), e))
log.debug(traceback.print_exc())
hs = False
else:
if not hs:
log.warning("bad handshake or timeout between: {} and {}".format(
fmt_addr(addr_master), fmt_addr(addr_slaver)))
if not hs:
# handshake failed or timeout
del self.spare_slaver_pool[addr_slaver]
try_close(conn_slaver)
log.warning("a slaver[{}] abort due to handshake error or timeout".format(
fmt_addr(addr_slaver)))
return
else:
log.info("Success master handshake from: {} to {}".format(
fmt_addr(addr_master), fmt_addr(addr_slaver)))
# ----------- slaver activated! ------------
# move self from spare_slaver_pool to working_pool
self.working_pool[addr_slaver] = self.spare_slaver_pool.pop(addr_slaver)
# ----------- connecting to target ----------
try:
conn_target = self._connect_target()
except:
log.error("unable to connect target")
try_close(conn_slaver)
del self.working_pool[addr_slaver]
return
self.working_pool[addr_slaver]["conn_target"] = conn_target
# ----------- all preparation finished -----------
# pass two sockets to SocketBridge, and let it do the
# real data exchange task
self.socket_bridge.add_conn_pair(
conn_slaver, conn_target,
functools.partial(
# 这个回调用来在传输完成后删除工作池中对应记录
self._transfer_complete, addr_slaver
)
)
# this slaver thread exits here
return
def serve_forever(self):
self.socket_bridge.start_as_daemon() # hi, don't ignore me
# sleep between two retries if exception occurs
# eg: master down or network temporary failed
# err_delay would increase if err occurs repeatedly
# until `max_err_delay`
# would immediately decrease to 0 after a success connection
err_delay = 0
max_err_delay = 15
# spare_delay is sleep cycle if we are full of spare slaver
# would immediately decrease to 0 after a slaver lack
spare_delay = 0.08
default_spare_delay = 0.08
while True:
if len(self.spare_slaver_pool) >= self.max_spare_count:
time.sleep(spare_delay)
spare_delay = (spare_delay + default_spare_delay) / 2.0
continue
else:
spare_delay = 0.0
try:
conn_slaver = self._connect_master()
except Exception as e:
log.warning("unable to connect master {}".format(e))
log.debug(traceback.format_exc())
time.sleep(err_delay)
if err_delay < max_err_delay:
err_delay += 1
continue
try:
t = threading.Thread(target=self._slaver_working,
args=(conn_slaver,)
)
t.daemon = True
t.start()
log.info("connected to master[{}] at {} total: {}".format(
fmt_addr(conn_slaver.getpeername()),
fmt_addr(conn_slaver.getsockname()),
len(self.spare_slaver_pool),
))
except Exception as e:
log.error("unable create Thread: {}".format(e))
log.debug(traceback.format_exc())
time.sleep(err_delay)
if err_delay < max_err_delay:
err_delay += 1
continue
# set err_delay if everything is ok
err_delay = 0
def run_slaver(communicate_addr, target_addr, max_spare_count=5):
log.info("running as slaver, master addr: {} target: {}".format(
fmt_addr(communicate_addr), fmt_addr(target_addr)
))
Slaver(communicate_addr, target_addr, max_spare_count=max_spare_count).serve_forever()
def argparse_slaver():
import argparse
parser = argparse.ArgumentParser(
description="""shootback {ver}-slaver
A fast and reliable reverse TCP tunnel (this is slaver)
Help access local-network service from Internet.
https://github.com/aploium/shootback""".format(ver=version_info()),
epilog="""
Example1:
tunnel local ssh to public internet, assume master's ip is 1.2.3.4
Master(another public server): master.py -m 0.0.0.0:10000 -c 0.0.0.0:10022
Slaver(this pc): slaver.py -m 1.2.3.4:10000 -t 127.0.0.1:22
Customer(any internet user): ssh 1.2.3.4 -p 10022
the actual traffic is: customer <--> master(1.2.3.4) <--> slaver(this pc) <--> ssh(this pc)
Example2:
Tunneling for www.example.com
Master(this pc): master.py -m 127.0.0.1:10000 -c 127.0.0.1:10080
Slaver(this pc): slaver.py -m 127.0.0.1:10000 -t example.com:80
Customer(this pc): curl -v -H "host: example.com" 127.0.0.1:10080
Tips: ANY service using TCP is shootback-able. HTTP/FTP/Proxy/SSH/VNC/...
""",
formatter_class=argparse.RawDescriptionHelpFormatter
)
parser.add_argument("-m", "--master", required=True,
metavar="host:port",
help="master address, usually an Public-IP. eg: 2.3.3.3:5500")
parser.add_argument("-t", "--target", required=True,
metavar="host:port",
help="where the traffic from master should be tunneled to, usually not public. eg: 10.1.2.3:80")
parser.add_argument("-k", "--secretkey", default="shootback",
help="secretkey to identity master and slaver, should be set to the same value in both side")
parser.add_argument("-v", "--verbose", action="count", default=0,
help="verbose output")
parser.add_argument("-q", "--quiet", action="count", default=0,
help="quiet output, only display warning and errors, use two to disable output")
parser.add_argument("-V", "--version", action="version", version="shootback {}-slaver".format(version_info()))
parser.add_argument("--ttl", default=300, type=int, dest="SPARE_SLAVER_TTL",
help="standing-by slaver's TTL, default is 300. "
"this value is optimized for most cases")
parser.add_argument("--max-standby", default=5, type=int, dest="max_spare_count",
help="max standby slaver TCP connections count, default is 5. "
"which is enough for more than 800 concurrency. "
"while working connections are always unlimited")
return parser.parse_args()
def main_slaver():
global SPARE_SLAVER_TTL
global SECRET_KEY
args = argparse_slaver()
if args.verbose and args.quiet:
print("-v and -q should not appear together")
exit(1)
communicate_addr = split_host(args.master)
target_addr = split_host(args.target)
SECRET_KEY = args.secretkey
CtrlPkg.recalc_crc32()
SPARE_SLAVER_TTL = args.SPARE_SLAVER_TTL
max_spare_count = args.max_spare_count
if args.quiet < 2:
if args.verbose:
level = logging.DEBUG
elif args.quiet:
level = logging.WARNING
else:
level = logging.INFO
configure_logging(level)
log.info("shootback {} slaver running".format(version_info()))
log.info("author: {} site: {}".format(__author__, __website__))
log.info("Master: {}".format(fmt_addr(communicate_addr)))
log.info("Target: {}".format(fmt_addr(target_addr)))
# communicate_addr = ("localhost", 12345)
# target_addr = ("93.184.216.34", 80) # www.example.com
run_slaver(communicate_addr, target_addr, max_spare_count=max_spare_count)
if __name__ == '__main__':
main_slaver()