mtg

README

mtg

Bullshit-free MTPROTO proxy for Telegram

Please see a guide on upgrading to 1.0 at the end of this README.

Rationale

There are several available proxies for Telegram MTPROTO available. Here are the most notable:

• Official
• Python
• Erlang

Almost all of them follow the way how official proxy was built. This includes support of multiple secrets, support of promoted channels, etc.

mtg is an implementation in golang which is intended to be:

• Lightweight It has to consume as few resources as possible but not by losing maintainability.
• Easily deployable I strongly believe that Telegram proxies should follow the way of ShadowSocks: promoted channels is a strange way of doing business I suppose. I think the only viable way is to have a proxy with minimum configuration which should work everywhere.
• A single secret I think that multiple secrets solve no problems and just complexify software. I also believe that in the case of throwout proxies, this feature is a useless luxury.
• Minimum docker image size Official image is less than 3.5 megabytes. Literally.
• No management WebUI This is an implementation of a simple lightweight proxy. I won't do that.

This proxy supports 2 modes of work: direct connection to Telegram and promoted channel mode. If you do not need promoted channels, I would recommend you to go with direct mode: this way is more robust.

To run a proxy in direct mode, all you need to do is just provide a secret. If you do not provide ADTag as a second parameter, promoted channels mode won't be activated.

To get promoted channel, please contact @MTProxybot and provide generated adtag as a second parameter.

Source code organization

There are 2 main branches:

1. master branch contains potentially unstable features
2. stable branch contains stable version. Usually you want to use this branch.

How to build

make

If you want to build for another platform:

make crosscompile

If you want to build Docker image (called mtg):

make docker

Docker image

Docker follows the same policy as the source code organization:

• latest mirrors the master branch
• stable mirrors the stable branch
• tags are for tagged releases

docker pull nineseconds/mtg:latest

docker pull nineseconds/mtg:stable

docker pull nineseconds/mtg:0.10

Ansible role

You can find unofficial Ansible role for mtg here: https://github.com/rlex/ansible-role-mtg Also, there is another project on Ansible Galaxy: https://galaxy.ansible.com/ivansible/lin_mtproxy

Configuration

To run this tool you need to configure as less as possible. Telegram clients support 3 different secret types:

• Simple - basically, it is just a flow of frames ciphered by AES-CTR stream cipher.
• Secured - the same stream as simple but with some random noise to prevent statistical analysis of traffic flow.
• FakeTLS - this mode envelops telegram stream in TLS so it looks (in theory) the same as any TLS1.3 traffic from DPI point of view.

If you do not have preferences, go with FakeTLS or at least secured. Simple mode is a little bit naive and traffic flow can be easily identified as Telegram one.

Unlike the rest of implementation, mtg is quite strict about the execution mode: if you run a proxy instance with FakeTLS secret, you can't connect to it with simple or secured clients. You can't connect to the proxy with secured secret with FakeTLS key. It forces one mode of working. So, unfortunately, there is no way how to connect to the deployed proxy with another secret (if you know how to construct and convert them). But at the same time, old clients can't connect so they won't expose the type of the service.

First, you need to generate a secret:

$ mtg generate-secret simple
52a493bdfb90eea55739eabff2d92a14

$ mtg generate-secret secured
ddf05fb7acb549be047a7c585116581418

$ mtg generate-secret -c google.com tls
ee852380f362a09343efb4690c4e17862e676f6f676c652e636f6d

Or, if you prefer docker:

$ docker run --rm nineseconds/mtg generate-secret tls -c bing.com
eedf71035a8ed48a623d8e83e66aec4d0562696e672e636f6d

Antireplay cache

To prevent replay attacks, we have internal storage of first frames messages for connected clients. These frames are generated randomly by design and we have the negligible possibility of duplication (probability is 1/(2^64)) but it could be quite effective to prevent replays.

It is possible to disable this cache. To do that, please explicitly set its size to 0.

FakeTLS

If you run this a proxy in faketls mode, this proxy will try to hide itself cloaking a host provided as a part of the generated secret. It means that if you cloak google.com then you can curl this proxy and you'll get a google.com response back.

mtg proxies L3 traffic. In other words, only TCP, without interfering in TLS, HTTP or any other high-level protocol.

Environment variables

It is possible to configure this tool using environment variables. You can configure any flag but not secret or adtag. Here is the list of supported environment variables:

Environment variable	Corresponding flags	Default value	Description
MTG_DEBUG	-d, --debug	false	Run in debug mode. Usually, you need to run in this mode only if you develop this tool or its maintainer is asking you to provide logs with such verbosity.
MTG_VERBOSE	-v, --verbose	false	Run in verbose mode. This is way less chatty than debug mode.
MTG_BIND	-b, --bind	0.0.0.0:3128	Which host/port pair should we bind to (listen on).
MTG_IPV4	-4, --public-ipv4	Autodetect	IPv4 address:port of this proxy. This is required if you NAT your proxy or run it in a docker container. In that case, you absolutely need to specify public IPv4 address of the proxy, otherwise either URLs will be broken or proxy could not access Telegram middle proxies.
MTG_IPV6	-6, --public-ipv6	Autodetect	IPv6 address:port of this proxy. This is required if you NAT your proxy or run it in a docker container. In that case, you absolutely need to specify public IPv6 address of the proxy, otherwise either URLs will be broken or proxy could not access Telegram middle proxies.
MTG_STATS_BIND	-t, --stats-bind	127.0.0.1:3129	Which hist:port should we bind the internal statistics HTTP server (Prometheus).
MTG_STATS_NAMESPACE	--stats-namespace	mtg	Which namespace should be used for prometheus metrics.
MTG_STATSD_ADDR	--statsd-addr		host:port of statsd service. No defaults, by default we do not send anything there.
MTG_STATSD_PREFIX	--statsd-prefix	mtg	Which bucket prefix we should use. For example, if you set mtg, then metric traffic.ingress would be send as mtg.traffic.ingress.
MTG_STATSD_TAGS_FORMAT	--statsd-tags-format		Which tags format we should use. By default, we are using default vanilla statsd tags format but if you want to send directly to InfluxDB or Datadog, please specify it there. Possible options are influxdb and datadog.
MTG_STATSD_TAGS	--statsd-tags		Which tags should we send to statsd with our metrics. Please specify them as key=value pairs.
MTG_BUFFER_WRITE	-w, --write-buffer	32KB	The size of TCP write buffer in bytes. Write buffer is the buffer for messages which are going from client to Telegram.
MTG_BUFFER_READ	-r, --read-buffer	32KB	The size of TCP read buffer in bytes. Read buffer is the buffer for messages from Telegram to client.
MTG_ANTIREPLAY_MAXSIZE	--anti-replay-max-size	128MB	Max size of antireplay cache.
MTG_CLOAK_PORT	--cloak-port	443	Which port we should use to connect to cloaked host in FakeTLS mode.
MTG_MULTIPLEX_PERCONNECTION	--multiplex-per-connection	50	How many client connections can share a single Telegram connection in adtag mode
MTG_NTP_SERVERS	--ntp-server	default pool	A list of NTP servers to use.
MTG_PREFER_DIRECT_IP	--prefer-ip	ipv6	Which IP protocol to prefer if possible. Works mostly in direct mode.

Usually you want to modify only read/write buffer sizes. If you feel that proxy is slow, try to increase both sizes giving more priority to read buffer.

Unfortunately, MTPROTO proxy protocol does not allow us to use splice or any other neat tricks how to eliminate the need of copying data into userspace.

How to run the tool

Now run the tool:

$ mtg run <secret>

How to run the tool with ADTag:

$ mtg run <secret> <adtag>

This tool will listen on port 3128 by default with the given secret.

oneliner to run this proxy

Please ensure that docker is installed. After that just execute

curl -sfL --compressed https://raw.githubusercontent.com/9seconds/mtg/master/run.sh | bash

statsd integration

mtg provides an integration with statsd, you can enable it with command line interface. To enable it, you have to provide IP address of statsd service.

Out of the box, mtg supports 2 additional dialects: InfluxDB and Datadog.

All metrics are gauges. Here is the list of metrics and their meaning:

Metric name	Unit	Description
connections	number	The number of active connections.
telegram_connections	number	The number of active telegram connections.
crashes	number	An amount of crashes in client handlers.
traffic.egress	bytes	Traffic from the start of application.
replay_attacks	number	The number of prevented replay attacks.

All metrics are prefixed with given prefix. Default prefix is mtg. Also, metrics provide tags (ipv4/ipv6, dc indexes etc).

Prometheus integration

Prometheus integration comes out of the box, you do not need to setup anything special.

Upgrade to 1.0

Version 1.0 breaks compatibility with previous versions so please read this chapter carefully:

1. mtg now uses subcommands. Please use mtg run instead of just mtg to run a proxy.
2. Options which set host and port separately were removed in a favor of fused host:port options.
3. Own stats server was removed. Prometheus endpoint is moved to default stats endpoint.
4. It is possible to connect to this proxy only with a secret which was used to run it. So, no backward compatibility of clients.
5. Multiplexing involves connectivity with middle proxies and involves the most complex code path of this proxy. To avoid potential bugs, we still recommend using direct mode.