remove the hackish logic against replay attacks because it stopped to work with new android clients

see https://github.com/alexbers/mtprotoproxy/issues/183

Dockerfile

@@ -7,6 +7,8 @@ RUN apk add --no-cache python3 py3-cryptography ca-certificates libcap
 RUN chown -R tgproxy:tgproxy /home/tgproxy
 RUN setcap cap_net_bind_service=+ep /usr/bin/python3.7
 
+COPY mtprotoproxy.py config.py /home/tgproxy/
+
 USER tgproxy
 
 WORKDIR /home/tgproxy/

README.md

@@ -20,6 +20,11 @@ To advertise a channel get a tag from **@MTProxybot** and put it to *config.py*.
 The proxy performance should be enough to comfortably serve about 4 000 simultaneous users on
 the VDS instance with 1 CPU core and 1024MB RAM.
 
+## More Instructions ##
+
+- [Running without Docker](https://github.com/alexbers/mtprotoproxy/wiki/Running-Without-Docker)
+- [Optimization and fine tuning](https://github.com/alexbers/mtprotoproxy/wiki/Optimization-and-Fine-Tuning)
+
 ## Advanced Usage ##
 
 The proxy can be launched:

config.py

@@ -1,20 +1,25 @@
-PORT = 3256
+PORT = 443
 
 # name -> secret (32 hex chars)
 USERS = {
-    "tg":  "00000000000000000000000000000000",
-    "tg2": "0123456789abcdef0123456789abcdef"
+    "tg":  "00000000000000000000000000000001",
+    # "tg2": "0123456789abcdef0123456789abcdef",
 }
 
-# Makes the proxy harder to detect
-# Can be incompatible with very old clients
-SECURE_ONLY = True
+MODES = {
+    # Classic mode, easy to detect
+    "classic": False,
 
-# Makes the proxy even more hard to detect
-# Compatible only with the recent clients
-TLS_ONLY = True
+    # Makes the proxy harder to detect
+    # Can be incompatible with very old clients
+    "secure": False,
 
-# The domain for TLS, bad clients are proxied there
+    # Makes the proxy even more hard to detect
+    # Can be incompatible with old clients
+    "tls": True
+}
+
+# The domain for TLS mode, bad clients are proxied there
 # Use random existing domain, proxy checks it on start
 # TLS_DOMAIN = "www.google.com"
 

mtprotoproxy.py

@@ -66,6 +66,8 @@ TLS_HANDSHAKE_LEN = 1 + 2 + 2 + 512
 PROTO_TAG_POS = 56
 DC_IDX_POS = 60
 
+MIN_CERT_LEN = 1024
+
 PROTO_TAG_ABRIDGED = b"\xef\xef\xef\xef"
 PROTO_TAG_INTERMEDIATE = b"\xee\xee\xee\xee"
 PROTO_TAG_SECURE = b"\xdd\xdd\xdd\xdd"
@@ -80,12 +82,13 @@ STAT_DURATION_BUCKETS = [0.1, 0.5, 1, 2, 5, 15, 60, 300, 600, 1800, 2**31 - 1]
 
 my_ip_info = {"ipv4": None, "ipv6": None}
 used_handshakes = collections.OrderedDict()
+client_ips = collections.OrderedDict()
+last_client_ips = {}
 disable_middle_proxy = False
 is_time_skewed = False
 fake_cert_len = random.randrange(1024, 4096)
 mask_host_cached_ip = None
 last_clients_with_time_skew = {}
-last_clients_with_first_pkt_error = collections.Counter()
 last_clients_with_same_handshake = collections.Counter()
 proxy_start_time = 0
 proxy_links = []
@@ -107,12 +110,12 @@ def init_config():
         conf_dict["PORT"] = int(sys.argv[1])
         secrets = sys.argv[2].split(",")
         conf_dict["USERS"] = {"user%d" % i: secrets[i].zfill(32) for i in range(len(secrets))}
+        conf_dict["MODES"] = {"classic": False, "secure": True, "tls": True}
         if len(sys.argv) > 3:
             conf_dict["AD_TAG"] = sys.argv[3]
         if len(sys.argv) > 4:
             conf_dict["TLS_DOMAIN"] = sys.argv[4]
-            conf_dict["TLS_ONLY"] = True
-        conf_dict["SECURE_ONLY"] = True
+            conf_dict["MODES"] = {"classic": False, "secure": False, "tls": True}
 
     conf_dict = {k: v for k, v in conf_dict.items() if k.isupper()}
 
@@ -131,11 +134,43 @@ def init_config():
     # disables tg->client trafic reencryption, faster but less secure
     conf_dict.setdefault("FAST_MODE", True)
 
-    # doesn't allow to connect in not-secure mode
-    conf_dict.setdefault("SECURE_ONLY", False)
+    # enables some working modes
+    modes = conf_dict.get("MODES", {})
 
-    # allows to connect in tls mode only
-    conf_dict.setdefault("TLS_ONLY", False)
+    if "MODES" not in conf_dict:
+        modes.setdefault("classic", True)
+        modes.setdefault("secure", True)
+        modes.setdefault("tls", True)
+    else:
+        modes.setdefault("classic", False)
+        modes.setdefault("secure", False)
+        modes.setdefault("tls", False)
+
+    legacy_warning = False
+    if "SECURE_ONLY" in conf_dict:
+        legacy_warning = True
+        modes["classic"] = not bool(conf_dict["SECURE_ONLY"])
+
+    if "TLS_ONLY" in conf_dict:
+        legacy_warning = True
+        if conf_dict["TLS_ONLY"]:
+            modes["classic"] = False
+            modes["secure"] = False
+
+    if not modes["classic"] and not modes["secure"] and not modes["tls"]:
+        print_err("No known modes enabled, enabling tls-only mode")
+        modes["tls"] = True
+
+    if legacy_warning:
+        print_err("Legacy options SECURE_ONLY or TLS_ONLY detected")
+        print_err("Please use MODES in your config instead:")
+        print_err("MODES = {")
+        print_err('    "classic": %s,' % modes["classic"])
+        print_err('    "secure": %s,' % modes["secure"])
+        print_err('    "tls": %s' % modes["tls"])
+        print_err("}")
+
+    conf_dict["MODES"] = modes
 
     # accept incoming connections only with proxy protocol v1/v2, useful for nginx and haproxy
     conf_dict.setdefault("PROXY_PROTOCOL", False)
@@ -178,8 +213,8 @@ def init_config():
     # length of used handshake randoms for active fingerprinting protection, zero to disable
     conf_dict.setdefault("REPLAY_CHECK_LEN", 65536)
 
-    # block bad first packets to even more protect against replay-based fingerprinting
-    conf_dict.setdefault("BLOCK_IF_FIRST_PKT_BAD", not conf_dict["TLS_ONLY"])
+    # length of last client ip addresses for logging
+    conf_dict.setdefault("CLIENT_IPS_LEN", 131072)
 
     # delay in seconds between stats printing
     conf_dict.setdefault("STATS_PRINT_PERIOD", 600)
@@ -236,6 +271,9 @@ def init_config():
     # export proxy link to prometheus
     conf_dict.setdefault("METRICS_EXPORT_LINKS", False)
 
+    # default prefix for metrics
+    conf_dict.setdefault("METRICS_PREFIX", "mtprotoproxy_")
+
     # allow access to config by attributes
     config = type("config", (dict,), conf_dict)(conf_dict)
 
@@ -431,6 +469,60 @@ class MyRandom(random.Random):
 myrandom = MyRandom()
 
 
+class TgConnectionPool:
+    MAX_CONNS_IN_POOL = 64
+
+    def __init__(self):
+        self.pools = {}
+
+    async def open_tg_connection(self, host, port, init_func=None):
+        task = asyncio.open_connection(host, port, limit=get_to_clt_bufsize())
+        reader_tgt, writer_tgt = await asyncio.wait_for(task, timeout=config.TG_CONNECT_TIMEOUT)
+
+        set_keepalive(writer_tgt.get_extra_info("socket"))
+        set_bufsizes(writer_tgt.get_extra_info("socket"), get_to_clt_bufsize(), get_to_tg_bufsize())
+
+        if init_func:
+            return await asyncio.wait_for(init_func(host, port, reader_tgt, writer_tgt),
+                                          timeout=config.TG_CONNECT_TIMEOUT)
+        return reader_tgt, writer_tgt
+
+    def register_host_port(self, host, port, init_func):
+        if (host, port, init_func) not in self.pools:
+            self.pools[(host, port, init_func)] = []
+
+        while len(self.pools[(host, port, init_func)]) < TgConnectionPool.MAX_CONNS_IN_POOL:
+            connect_task = asyncio.ensure_future(self.open_tg_connection(host, port, init_func))
+            self.pools[(host, port, init_func)].append(connect_task)
+
+    async def get_connection(self, host, port, init_func=None):
+        self.register_host_port(host, port, init_func)
+
+        ret = None
+        for task in self.pools[(host, port, init_func)][::]:
+            if task.done():
+                if task.exception():
+                    self.pools[(host, port, init_func)].remove(task)
+                    continue
+
+                reader, writer, *other = task.result()
+                if writer.transport.is_closing():
+                    self.pools[(host, port, init_func)].remove(task)
+                    continue
+
+                if not ret:
+                    self.pools[(host, port, init_func)].remove(task)
+                    ret = (reader, writer, *other)
+
+        self.register_host_port(host, port, init_func)
+        if ret:
+            return ret
+        return await self.open_tg_connection(host, port, init_func)
+
+
+tg_connection_pool = TgConnectionPool()
+
+
 class LayeredStreamReaderBase:
     __slots__ = ("upstream", )
 
@@ -972,6 +1064,8 @@ async def handle_bad_client(reader_clt, writer_clt, handshake):
 
 async def handle_fake_tls_handshake(handshake, reader, writer, peer):
     global used_handshakes
+    global client_ips
+    global last_client_ips
     global last_clients_with_time_skew
     global last_clients_with_same_handshake
     global fake_cert_len
@@ -1044,6 +1138,13 @@ async def handle_fake_tls_handshake(handshake, reader, writer, peer):
                 used_handshakes.popitem(last=False)
             used_handshakes[digest[:DIGEST_HALFLEN]] = True
 
+        if config.CLIENT_IPS_LEN > 0:
+            while len(client_ips) >= config.CLIENT_IPS_LEN:
+                client_ips.popitem(last=False)
+            if peer[0] not in client_ips:
+                client_ips[peer[0]] = True
+                last_client_ips[peer[0]] = True
+
         reader = FakeTLSStreamReader(reader)
         writer = FakeTLSStreamWriter(writer)
         return reader, writer
@@ -1108,6 +1209,8 @@ async def handle_proxy_protocol(reader, peer=None):
 
 async def handle_handshake(reader, writer):
     global used_handshakes
+    global client_ips
+    global last_client_ips
     global last_clients_with_same_handshake
 
     TLS_START_BYTES = b"\x16\x03\x01\x02\x00\x01\x00\x01\xfc\x03\x03"
@@ -1143,7 +1246,7 @@ async def handle_handshake(reader, writer):
         reader, writer = tls_handshake_result
         handshake = await reader.readexactly(HANDSHAKE_LEN)
     else:
-        if config.TLS_ONLY:
+        if not config.MODES["classic"] and not config.MODES["secure"]:
             await handle_bad_client(reader, writer, handshake)
             return False
         handshake += await reader.readexactly(HANDSHAKE_LEN - len(handshake))
@@ -1173,8 +1276,14 @@ async def handle_handshake(reader, writer):
         if proto_tag not in (PROTO_TAG_ABRIDGED, PROTO_TAG_INTERMEDIATE, PROTO_TAG_SECURE):
             continue
 
-        if config.SECURE_ONLY and proto_tag != PROTO_TAG_SECURE:
-            continue
+        if proto_tag == PROTO_TAG_SECURE:
+            if is_tls_handshake and not config.MODES["tls"]:
+                continue
+            if not is_tls_handshake and not config.MODES["secure"]:
+                continue
+        else:
+            if not config.MODES["classic"]:
+                continue
 
         dc_idx = int.from_bytes(decrypted[DC_IDX_POS:DC_IDX_POS+2], "little", signed=True)
 
@@ -1183,6 +1292,13 @@ async def handle_handshake(reader, writer):
                 used_handshakes.popitem(last=False)
             used_handshakes[dec_prekey_and_iv] = True
 
+        if config.CLIENT_IPS_LEN > 0:
+            while len(client_ips) >= config.CLIENT_IPS_LEN:
+                client_ips.popitem(last=False)
+            if peer[0] not in client_ips:
+                client_ips[peer[0]] = True
+                last_client_ips[peer[0]] = True
+
         reader = CryptoWrappedStreamReader(reader, decryptor)
         writer = CryptoWrappedStreamWriter(writer, encryptor)
         return reader, writer, proto_tag, user, dc_idx, enc_key + enc_iv, peer
@@ -1191,21 +1307,6 @@ async def handle_handshake(reader, writer):
     return False
 
 
-async def open_connection_tryer(addr, port, limit, timeout, max_attempts=3):
-    for attempt in range(max_attempts-1):
-        try:
-            task = asyncio.open_connection(addr, port, limit=limit)
-            reader_tgt, writer_tgt = await asyncio.wait_for(task, timeout=timeout)
-            return reader_tgt, writer_tgt
-        except (OSError, asyncio.TimeoutError):
-            continue
-
-    # the last attempt
-    task = asyncio.open_connection(addr, port, limit=limit)
-    reader_tgt, writer_tgt = await asyncio.wait_for(task, timeout=timeout)
-    return reader_tgt, writer_tgt
-
-
 async def do_direct_handshake(proto_tag, dc_idx, dec_key_and_iv=None):
     RESERVED_NONCE_FIRST_CHARS = [b"\xef"]
     RESERVED_NONCE_BEGININGS = [b"\x48\x45\x41\x44", b"\x50\x4F\x53\x54",
@@ -1214,6 +1315,7 @@ async def do_direct_handshake(proto_tag, dc_idx, dec_key_and_iv=None):
     RESERVED_NONCE_CONTINUES = [b"\x00\x00\x00\x00"]
 
     global my_ip_info
+    global tg_connection_pool
 
     dc_idx = abs(dc_idx) - 1
 
@@ -1227,18 +1329,17 @@ async def do_direct_handshake(proto_tag, dc_idx, dec_key_and_iv=None):
         dc = TG_DATACENTERS_V4[dc_idx]
 
     try:
-        reader_tgt, writer_tgt = await open_connection_tryer(
-            dc, TG_DATACENTER_PORT, limit=get_to_clt_bufsize(), timeout=config.TG_CONNECT_TIMEOUT)
+        reader_tgt, writer_tgt = await tg_connection_pool.get_connection(dc, TG_DATACENTER_PORT)
     except ConnectionRefusedError as E:
         print_err("Got connection refused while trying to connect to", dc, TG_DATACENTER_PORT)
         return False
+    except ConnectionAbortedError as E:
+        print_err("The Telegram server connection is bad: %d (%s %s) %s" % (dc_idx, addr, port, E))
+        return False
     except (OSError, asyncio.TimeoutError) as E:
         print_err("Unable to connect to", dc, TG_DATACENTER_PORT)
         return False
 
-    set_keepalive(writer_tgt.get_extra_info("socket"))
-    set_bufsizes(writer_tgt.get_extra_info("socket"), get_to_clt_bufsize(), get_to_tg_bufsize())
-
     while True:
         rnd = bytearray(myrandom.getrandbytes(HANDSHAKE_LEN))
         if rnd[:1] in RESERVED_NONCE_FIRST_CHARS:
@@ -1301,49 +1402,21 @@ def get_middleproxy_aes_key_and_iv(nonce_srv, nonce_clt, clt_ts, srv_ip, clt_por
     return key, iv
 
 
-async def do_middleproxy_handshake(proto_tag, dc_idx, cl_ip, cl_port):
+async def middleproxy_handshake(host, port, reader_tgt, writer_tgt):
+    """ The most logic of middleproxy handshake, launched in pool """
     START_SEQ_NO = -2
     NONCE_LEN = 16
 
-    RPC_NONCE = b"\xaa\x87\xcb\x7a"
     RPC_HANDSHAKE = b"\xf5\xee\x82\x76"
+    RPC_NONCE = b"\xaa\x87\xcb\x7a"
+    # pass as consts to simplify code
+    RPC_FLAGS = b"\x00\x00\x00\x00"
     CRYPTO_AES = b"\x01\x00\x00\x00"
 
     RPC_NONCE_ANS_LEN = 32
     RPC_HANDSHAKE_ANS_LEN = 32
 
-    # pass as consts to simplify code
-    RPC_FLAGS = b"\x00\x00\x00\x00"
-
-    global my_ip_info
-
-    use_ipv6_tg = (my_ip_info["ipv6"] and (config.PREFER_IPV6 or not my_ip_info["ipv4"]))
-    use_ipv6_clt = (":" in cl_ip)
-
-    if use_ipv6_tg:
-        if dc_idx not in TG_MIDDLE_PROXIES_V6:
-            return False
-        addr, port = myrandom.choice(TG_MIDDLE_PROXIES_V6[dc_idx])
-    else:
-        if dc_idx not in TG_MIDDLE_PROXIES_V4:
-            return False
-        addr, port = myrandom.choice(TG_MIDDLE_PROXIES_V4[dc_idx])
-
-    try:
-        reader_tgt, writer_tgt = await open_connection_tryer(addr, port, limit=get_to_clt_bufsize(),
-                                                             timeout=config.TG_CONNECT_TIMEOUT)
-    except ConnectionRefusedError as E:
-        print_err("The Telegram server %d (%s %s) is refusing connections" % (dc_idx, addr, port))
-        return False
-    except (OSError, asyncio.TimeoutError) as E:
-        print_err("Unable to connect to the Telegram server %d (%s %s)" % (dc_idx, addr, port))
-        return False
-
-    set_keepalive(writer_tgt.get_extra_info("socket"))
-    set_bufsizes(writer_tgt.get_extra_info("socket"), get_to_clt_bufsize(), get_to_tg_bufsize())
-
     writer_tgt = MTProtoFrameStreamWriter(writer_tgt, START_SEQ_NO)
-
     key_selector = PROXY_SECRET[:4]
     crypto_ts = int.to_bytes(int(time.time()) % (256**4), 4, "little")
 
@@ -1354,24 +1427,25 @@ async def do_middleproxy_handshake(proto_tag, dc_idx, cl_ip, cl_port):
     writer_tgt.write(msg)
     await writer_tgt.drain()
 
-    old_reader = reader_tgt
     reader_tgt = MTProtoFrameStreamReader(reader_tgt, START_SEQ_NO)
     ans = await reader_tgt.read(get_to_clt_bufsize())
 
     if len(ans) != RPC_NONCE_ANS_LEN:
-        return False
+        raise ConnectionAbortedError("bad rpc answer length")
 
     rpc_type, rpc_key_selector, rpc_schema, rpc_crypto_ts, rpc_nonce = (
         ans[:4], ans[4:8], ans[8:12], ans[12:16], ans[16:32]
     )
 
     if rpc_type != RPC_NONCE or rpc_key_selector != key_selector or rpc_schema != CRYPTO_AES:
-        return False
+        raise ConnectionAbortedError("bad rpc answer")
 
     # get keys
     tg_ip, tg_port = writer_tgt.upstream.get_extra_info('peername')[:2]
     my_ip, my_port = writer_tgt.upstream.get_extra_info('sockname')[:2]
 
+    use_ipv6_tg = (":" in tg_ip)
+
     if not use_ipv6_tg:
         if my_ip_info["ipv4"]:
             # prefer global ip settings to work behind NAT
@@ -1422,11 +1496,42 @@ async def do_middleproxy_handshake(proto_tag, dc_idx, cl_ip, cl_port):
 
     handshake_ans = await reader_tgt.read(1)
     if len(handshake_ans) != RPC_HANDSHAKE_ANS_LEN:
-        return False
+        raise ConnectionAbortedError("bad rpc handshake answer length")
 
     handshake_type, handshake_flags, handshake_sender_pid, handshake_peer_pid = (
         handshake_ans[:4], handshake_ans[4:8], handshake_ans[8:20], handshake_ans[20:32])
     if handshake_type != RPC_HANDSHAKE or handshake_peer_pid != SENDER_PID:
+        raise ConnectionAbortedError("bad rpc handshake answer")
+
+    return reader_tgt, writer_tgt, my_ip, my_port
+
+
+async def do_middleproxy_handshake(proto_tag, dc_idx, cl_ip, cl_port):
+    global my_ip_info
+    global tg_connection_pool
+
+    use_ipv6_tg = (my_ip_info["ipv6"] and (config.PREFER_IPV6 or not my_ip_info["ipv4"]))
+
+    if use_ipv6_tg:
+        if dc_idx not in TG_MIDDLE_PROXIES_V6:
+            return False
+        addr, port = myrandom.choice(TG_MIDDLE_PROXIES_V6[dc_idx])
+    else:
+        if dc_idx not in TG_MIDDLE_PROXIES_V4:
+            return False
+        addr, port = myrandom.choice(TG_MIDDLE_PROXIES_V4[dc_idx])
+
+    try:
+        ret = await tg_connection_pool.get_connection(addr, port, middleproxy_handshake)
+        reader_tgt, writer_tgt, my_ip, my_port = ret
+    except ConnectionRefusedError as E:
+        print_err("The Telegram server %d (%s %s) is refusing connections" % (dc_idx, addr, port))
+        return False
+    except ConnectionAbortedError as E:
+        print_err("The Telegram server connection is bad: %d (%s %s) %s" % (dc_idx, addr, port, E))
+        return False
+    except (OSError, asyncio.TimeoutError) as E:
+        print_err("Unable to connect to the Telegram server %d (%s %s)" % (dc_idx, addr, port))
         return False
 
     writer_tgt = ProxyReqStreamWriter(writer_tgt, cl_ip, cl_port, my_ip, my_port, proto_tag)
@@ -1497,9 +1602,7 @@ async def handle_client(reader_clt, writer_clt):
         else:
             return
 
-    async def connect_reader_to_writer(rd, wr, user, rd_buf_size, block_if_first_pkt_bad=False):
-        global last_clients_with_first_pkt_error
-        is_first_pkt = True
+    async def connect_reader_to_writer(rd, wr, user, rd_buf_size):
         try:
             while True:
                 data = await rd.read(rd_buf_size)
@@ -1508,18 +1611,6 @@ async def handle_client(reader_clt, writer_clt):
                 else:
                     extra = {}
 
-                # protection against replay-based fingerprinting
-                if is_first_pkt:
-                    is_first_pkt = False
-
-                    ERR_PKT_DATA = b'l\xfe\xff\xff'
-                    if block_if_first_pkt_bad and data == ERR_PKT_DATA:
-                        last_clients_with_first_pkt_error[cl_ip] += 1
-
-                        wr.write_eof()
-                        await wr.drain()
-                        return
-
                 if not data:
                     wr.write_eof()
                     await wr.drain()
@@ -1528,12 +1619,11 @@ async def handle_client(reader_clt, writer_clt):
                     update_user_stats(user, octets=len(data), msgs=1)
                     wr.write(data, extra)
                     await wr.drain()
-        except (OSError, asyncio.streams.IncompleteReadError) as e:
+        except (OSError, asyncio.IncompleteReadError) as e:
             # print_err(e)
             pass
 
-    tg_to_clt = connect_reader_to_writer(reader_tg, writer_clt, user, get_to_clt_bufsize(),
-                                         block_if_first_pkt_bad=config.BLOCK_IF_FIRST_PKT_BAD)
+    tg_to_clt = connect_reader_to_writer(reader_tg, writer_clt, user, get_to_clt_bufsize())
     clt_to_tg = connect_reader_to_writer(reader_clt, writer_tg, user, get_to_tg_bufsize())
     task_tg_to_clt = asyncio.ensure_future(tg_to_clt)
     task_clt_to_tg = asyncio.ensure_future(clt_to_tg)
@@ -1586,6 +1676,7 @@ def make_metrics_pkt(metrics):
     used_names = set()
 
     for name, m_type, desc, val in metrics:
+        name = config.METRICS_PREFIX + name
         if name not in used_names:
             pkt_body_list.append("# HELP %s %s" % (name, desc))
             pkt_body_list.append("# TYPE %s %s" % (name, m_type))
@@ -1622,7 +1713,6 @@ async def handle_metrics(reader, writer):
     global proxy_start_time
     global proxy_links
     global last_clients_with_time_skew
-    global last_clients_with_first_pkt_error
     global last_clients_with_same_handshake
 
     client_ip = writer.get_extra_info("peername")[0]
@@ -1680,8 +1770,8 @@ async def handle_metrics(reader, writer):
 
 async def stats_printer():
     global user_stats
+    global last_client_ips
     global last_clients_with_time_skew
-    global last_clients_with_first_pkt_error
     global last_clients_with_same_handshake
 
     while True:
@@ -1694,18 +1784,19 @@ async def stats_printer():
                 stat["octets"] / 1000000, stat["msgs"]))
         print(flush=True)
 
+        if last_client_ips:
+            print("New IPs:")
+            for ip in last_client_ips:
+                print(ip)
+            print(flush=True)
+            last_client_ips.clear()
+
         if last_clients_with_time_skew:
             print("Clients with time skew (possible replay-attackers):")
             for ip, skew_minutes in last_clients_with_time_skew.items():
                 print("%s, clocks were %d minutes behind" % (ip, skew_minutes))
             print(flush=True)
             last_clients_with_time_skew.clear()
-        if last_clients_with_first_pkt_error:
-            print("Clients with error on the first packet (possible replay-attackers):")
-            for ip, times in last_clients_with_first_pkt_error.items():
-                print("%s, %d times" % (ip, times))
-            print(flush=True)
-            last_clients_with_first_pkt_error.clear()
         if last_clients_with_same_handshake:
             print("Clients with duplicate handshake (likely replay-attackers):")
             for ip, times in last_clients_with_same_handshake.items():
@@ -1803,7 +1894,11 @@ async def get_mask_host_cert_len():
             task = get_encrypted_cert(config.MASK_HOST, config.MASK_PORT, config.TLS_DOMAIN)
             cert = await asyncio.wait_for(task, timeout=GET_CERT_TIMEOUT)
             if cert:
-                if len(cert) != fake_cert_len:
+                if len(cert) < MIN_CERT_LEN:
+                    msg = ("The MASK_HOST %s returned several TLS records, this is not supported" %
+                           config.MASK_HOST)
+                    print_err(msg)
+                elif len(cert) != fake_cert_len:
                     fake_cert_len = len(cert)
                     print_err("Got cert from the MASK_HOST %s, its length is %d" %
                               (config.MASK_HOST, fake_cert_len))
@@ -1965,7 +2060,7 @@ def print_tg_info():
 
     if config.PORT == 3256:
         print("The default port 3256 is used, this is not recommended", flush=True)
-        if config.TLS_ONLY:
+        if not config.MODES["classic"] and not config.MODES["secure"]:
             print("Since you have TLS only mode enabled the best port is 443", flush=True)
         print_default_warning = True
 
@@ -1977,31 +2072,33 @@ def print_tg_info():
 
     for user, secret in sorted(config.USERS.items(), key=lambda x: x[0]):
         for ip in ip_addrs:
-            if not config.TLS_ONLY:
-                if not config.SECURE_ONLY:
-                    params = {"server": ip, "port": config.PORT, "secret": secret}
-                    params_encodeded = urllib.parse.urlencode(params, safe=':')
-                    classic_link = "tg://proxy?{}".format(params_encodeded)
-                    proxy_links.append({"user": user, "link": classic_link})
-                    print("{}: {}".format(user, classic_link), flush=True)
+            if config.MODES["classic"]:
+                params = {"server": ip, "port": config.PORT, "secret": secret}
+                params_encodeded = urllib.parse.urlencode(params, safe=':')
+                classic_link = "tg://proxy?{}".format(params_encodeded)
+                proxy_links.append({"user": user, "link": classic_link})
+                print("{}: {}".format(user, classic_link), flush=True)
 
+            if config.MODES["secure"]:
                 params = {"server": ip, "port": config.PORT, "secret": "dd" + secret}
                 params_encodeded = urllib.parse.urlencode(params, safe=':')
                 dd_link = "tg://proxy?{}".format(params_encodeded)
                 proxy_links.append({"user": user, "link": dd_link})
                 print("{}: {}".format(user, dd_link), flush=True)
 
-            tls_secret = "ee" + secret + config.TLS_DOMAIN.encode().hex()
-            # the base64 links is buggy on ios
-            # tls_secret = bytes.fromhex("ee" + secret) + config.TLS_DOMAIN.encode()
-            # tls_secret_base64 = base64.urlsafe_b64encode(tls_secret)
-            params = {"server": ip, "port": config.PORT, "secret": tls_secret}
-            params_encodeded = urllib.parse.urlencode(params, safe=':')
-            tls_link = "tg://proxy?{}".format(params_encodeded)
-            proxy_links.append({"user": user, "link": tls_link})
-            print("{}: {}".format(user, tls_link), flush=True)
+            if config.MODES["tls"]:
+                tls_secret = "ee" + secret + config.TLS_DOMAIN.encode().hex()
+                # the base64 links is buggy on ios
+                # tls_secret = bytes.fromhex("ee" + secret) + config.TLS_DOMAIN.encode()
+                # tls_secret_base64 = base64.urlsafe_b64encode(tls_secret)
+                params = {"server": ip, "port": config.PORT, "secret": tls_secret}
+                params_encodeded = urllib.parse.urlencode(params, safe=':')
+                tls_link = "tg://proxy?{}".format(params_encodeded)
+                proxy_links.append({"user": user, "link": tls_link})
+                print("{}: {}".format(user, tls_link), flush=True)
 
-        if secret in ["00000000000000000000000000000000", "0123456789abcdef0123456789abcdef"]:
+        if secret in ["00000000000000000000000000000000", "0123456789abcdef0123456789abcdef",
+                      "00000000000000000000000000000001"]:
             msg = "The default secret {} is used, this is not recommended".format(secret)
             print(msg, flush=True)
             random_secret = "".join(myrandom.choice("0123456789abcdef") for i in range(32))
@@ -2133,29 +2230,29 @@ def main():
 
     if config.LISTEN_ADDR_IPV4:
         task = asyncio.start_server(handle_client_wrapper, config.LISTEN_ADDR_IPV4, config.PORT,
-                                    limit=get_to_tg_bufsize(), reuse_port=reuse_port, loop=loop)
+                                    limit=get_to_tg_bufsize(), reuse_port=reuse_port)
         servers.append(loop.run_until_complete(task))
 
     if config.LISTEN_ADDR_IPV6 and socket.has_ipv6:
         task = asyncio.start_server(handle_client_wrapper, config.LISTEN_ADDR_IPV6, config.PORT,
-                                    limit=get_to_tg_bufsize(), reuse_port=reuse_port, loop=loop)
+                                    limit=get_to_tg_bufsize(), reuse_port=reuse_port)
         servers.append(loop.run_until_complete(task))
 
     if config.LISTEN_UNIX_SOCK and has_unix:
         remove_unix_socket(config.LISTEN_UNIX_SOCK)
         task = asyncio.start_unix_server(handle_client_wrapper, config.LISTEN_UNIX_SOCK,
-                                         limit=get_to_tg_bufsize(), loop=loop)
+                                         limit=get_to_tg_bufsize())
         servers.append(loop.run_until_complete(task))
         os.chmod(config.LISTEN_UNIX_SOCK, 0o666)
 
     if config.METRICS_PORT is not None:
         if config.METRICS_LISTEN_ADDR_IPV4:
             task = asyncio.start_server(handle_metrics, config.METRICS_LISTEN_ADDR_IPV4,
-                                        config.METRICS_PORT, loop=loop)
+                                        config.METRICS_PORT)
             servers.append(loop.run_until_complete(task))
         if config.METRICS_LISTEN_ADDR_IPV6 and socket.has_ipv6:
             task = asyncio.start_server(handle_metrics, config.METRICS_LISTEN_ADDR_IPV6,
-                                        config.METRICS_PORT, loop=loop)
+                                        config.METRICS_PORT)
             servers.append(loop.run_until_complete(task))
 
     try: