Erlang mtproto proxy

This part of code was extracted from @socksy_bot.

Features

Promoted channels. See tag option.
"secure" randomized-packet-size protocol (34-symbol secrets starting with 'dd') to prevent detection by DPI
Fake-TLS protocol ('ee'/base64 secrets) - another protocol to prevent DPI detection
Secure-only mode (only allow connections with 'dd' or fake-TLS). See allowed_protocols option.
Connection limit policies - limit number of connections by IP / tls-domain / port; IP / tls-domain blacklists / whitelists
Multiple ports with unique secret and promo tag for each port
Very high performance - can handle tens of thousands connections! Scales to all CPU cores. 1Gbps, 90k connections on 4-core/8Gb RAM cloud server.
Supports multiplexing (Many connections Client -> Proxy are wrapped to small amount of connections Proxy -> Telegram Server) - lower pings and better OS network utilization
Protection from replay attacks used to detect proxies in some countries
Automatic telegram configuration reload (no need for restarts once per day)
IPv6 for client connections
All configuration options can be updated without service restart
Small codebase compared to official one, code is covered by automated tests
A lots of metrics could be exported (optional)

How to install - one-line interactive installer

This command will run interactive script that will install and configure proxy for your Ubuntu / Debian / CentOS server. It will ask if you want to change default port/secret/ad-tag/protocols:

curl -L -o mtp_install.sh https://git.io/fj5ru && bash mtp_install.sh

You can also just provide port/secret/ad-tag/protocols/tls-domain as command line arguments:

curl -L -o mtp_install.sh https://git.io/fj5ru && bash mtp_install.sh -p 443 -s d0d6e111bada5511fcce9584deadbeef -t dcbe8f1493fa4cd9ab300891c0b5b326 -a dd -a tls -d s3.amazonaws.com

It does the same as described in How to start OS-install - detailed, but generates config-file for you automatically.

How to start - Docker

To run with default settings

docker run -d --network=host seriyps/mtproto-proxy

To run on single port with custom port, secret and ad-tag

docker run -d --network=host seriyps/mtproto-proxy -p 443 -s d0d6e111bada5511fcce9584deadbeef -t dcbe8f1493fa4cd9ab300891c0b5b326

or via environment variables

docker run -d --network=host -e MTP_PORT=443 -e MTP_SECRET=d0d6e111bada5511fcce9584deadbeef -e MTP_TAG=dcbe8f1493fa4cd9ab300891c0b5b326 seriyps/mtproto-proxy

Where

-p 443 / MTP_PORT=… proxy port
-s d0d6e111bada5511fcce9584deadbeef / MTP_SECRET=… proxy secret (don't append dd! it should be 32 chars long!)
-t dcbe8f1493fa4cd9ab300891c0b5b326 / MTP_TAG=… ad-tag that you get from @MTProxybot
-a dd / MTP_DD_ONLY=t only allow "secure" connections (dd-secrets)
-a tls / MTP_TLS_ONLY=t only allow "fake-TLS" connections (base64 secrets)

It's ok to provide both -a dd -a tls to allow both protocols. If no -a option provided, all protocols will be allowed.

To run with custom config-file

Get the code git clone https://github.com/seriyps/mtproto_proxy.git && cd mtproto_proxy/
Copy config templates cp config/{vm.args.example,prod-vm.args}; cp config/{sys.config.example,prod-sys.config}
Edit configs. See Settings.
Build docker build -t mtproto-proxy-erl .
Start docker run -d --network=host mtproto-proxy-erl

Installation via docker can work well for small setups (10-20k connections), but for more heavily-loaded setups it's recommended to install proxy directly into your server's OS (see below).

How to start OS-install - quick

You need at least Erlang version 20! Recommended OS is Ubuntu 18.04.

sudo apt install erlang-nox erlang-dev build-essential
git clone https://github.com/seriyps/mtproto_proxy.git
cd mtproto_proxy/
cp config/vm.args.example config/prod-vm.args
cp config/sys.config.example config/prod-sys.config
# configure your port, secret, ad_tag. See [Settings](#settings) below.
nano config/prod-sys.config
make && sudo make install
sudo systemctl enable mtproto-proxy
sudo systemctl start mtproto-proxy

How to start OS-install - detailed

Install deps

Ubuntu 18.xx / Ubuntu 19.xx / Debian 10:

sudo apt install erlang-nox erlang-dev  make sed diffutils tar

CentOS 7

# Enable "epel" and "Erlang solutions" repositories
sudo yum install wget \
             https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm \
             https://packages.erlang-solutions.com/erlang-solutions-1.0-1.noarch.rpm
# Install Erlang
sudo yum install erlang-compiler erlang-erts erlang-kernel erlang-stdlib erlang-syntax_tools \
     erlang-crypto erlang-inets erlang-sasl erlang-ssl

You need Erlang version 20 or higher! If your version is older, please, check Erlang solutions esl-erlang package or use kerl.

Get the code:

git clone https://github.com/seriyps/mtproto_proxy.git
cd mtproto_proxy/

Create config file

see Settings.

Build and install

make && sudo make install

This will:

install proxy into /opt/mtp_proxy
create a system user
install systemd service
create a directory for logs in /var/log/mtproto-proxy
Configure ulimit of max open files and CAP_NET_BIND_SERVICE by systemd

Try to start in foreground mode

This step is optional, but it can be useful to test if everything works as expected

./start.sh

try to run ./start.sh -h to learn some useful options.

Start in background and enable start on system start-up

sudo systemctl enable mtproto-proxy
sudo systemctl start mtproto-proxy

Done! Proxy is up and ready to serve now!

Stop / uninstall

Stop:

sudo systemctl stop mtproto-proxy

Uninstall:

sudo systemctl stop mtproto-proxy
sudo systemctl disable mtproto-proxy
sudo make uninstall

Logs can be found at

/var/log/mtproto-proxy/application.log

Settings

All available documented configuration options could be found in src/mtproto_proxy.app.src. Do not edit this file!

To change configuration, edit config/prod-sys.config:

Comments in this file start with %%. Default port is 1443 and default secret is d0d6e111bada5511fcce9584deadbeef.

Secret key and proxy URLs will be printed on start.

Apply config changes without restart

It's possible to reload config file without service restart (but if you want to update ad_tag on existing port, all clients of this port will be disconnected).

This method doesn't work for Docker!

To do that, make changes in config/prod-sys.config and run following command:

sudo make update-sysconfig && sudo systemctl reload mtproto-proxy

Change default port / secret / ad tag

To change default settings, change mtproto_proxy section of prod-sys.config as:

 {mtproto_proxy,
  %% see src/mtproto_proxy.app.src for examples.
  [
   {ports,
    [#{name => mtp_handler_1,
       listen_ip => "0.0.0.0",
       port => 1443,
       secret => <<"d0d6e111bada5511fcce9584deadbeef">>,
       tag => <<"dcbe8f1493fa4cd9ab300891c0b5b326">>}
    ]}
   ]},

 {lager,
<...>

(so, remove %%s) and replace port / secret / tag with yours.

Listen on multiple ports / IPs

You can start proxy on many IP addresses or ports with different secrets/ad tags. To do so, just add more configs to ports section, separated by comma, eg:

 {mtproto_proxy,
  %% see src/mtproto_proxy.app.src for examples.
  [
   {ports,
    [#{name => mtp_handler_1,
       listen_ip => "0.0.0.0",
       port => 1443,
       secret => <<"d0d6e111bada5511fcce9584deadbeef">>,
       tag => <<"dcbe8f1493fa4cd9ab300891c0b5b326">>},
     #{name => mtp_handler_2,
       listen_ip => "0.0.0.0",
       port => 2443,
       secret => <<"100000000000000000000000000000001">>,
       tag => <<"cf8e6baff125ed5f661a761e69567711">>}
    ]}
   ]},

 {lager,
<...>

Each section should have unique name!

Only allow connections with 'dd'-secrets

This protocol uses randomized packet sizes, so it's more difficult to detect on DPI by packet sizes. It might be useful in Iran, where proxies are detected by DPI. You should disable all protocols other than mtp_secure by providing allowed_protocols option:

  {mtproto_proxy,
   [
    {allowed_protocols, [mtp_secure]},
    {ports,
     [#{name => mtp_handler_1,
      <..>

Only allow fake-TLS connections with ee/base64-secrets

Another censorship circumvention technique. MTPRoto proxy protocol pretends to be HTTPS web traffic (technically speaking, TLSv1.3 + HTTP/2). It's possible to only allow connections with this protocol by changing allowed_protocols to be list with only mtp_fake_tls.

  {mtproto_proxy,
   [
    {allowed_protocols, [mtp_fake_tls]},
    {ports,
     [#{name => mtp_handler_1,
      <..>

Connection limit policies

Proxy supports flexible connection limit rules. It's possible to limit number of connections from single IP or to single fake-TLS domain or to single port name; or any combination of them. It also supports whitelists and blacklists: you can allow or forbid to connect from some IP or IP subnet or with some TLS domains.

Policy is set as value of policy config key and the value is the list of policy structures. If list is empty, no limits will be checked.

Following policies are supported:

{in_table, KEY, TABLE_NAME} - only allow connections if KEY is present in TABLE_NAME (whitelist)
{not_in_table, KEY, TABLE_NAME} - only allow connections if KEY is not present in TABLE_NAME (blacklist)
{max_connections, KEYS, NUMBER} - EXPERIMENTAL! if there are more than NUMBER connections with KEYS to the proxy, new connections with those KEYS will be rejected. Note: number of connections is not the same as number of unique "users". When someone connects to proxy with telegram client, Telegram opens from 3 to 8 connections! So, you need to set this at least 8 * number of unique users.

Where:

KEY is one of:
- port_name - proxy port name
- client_ipv4 - client's IPv4 address; ignored on IPv6 ports!
- client_ipv6 - client's IPv6 address; ignored on IPv4 ports!
- {client_ipv4_subnet, MASK} - client's IPv4 subnet; mask is from 8 to 32
- {client_ipv6_subnet, MASK} - client's IPv6 subnet; mask is from 32 to 128
- tls_domain - lowercase domain name from fake-TLS secret; ignored if connection with non-fake-TLS protocol
KEYS is a list of one or more KEY, eg, [port, tls_domain]
TABLE_NAME is free-form text name of special internal database table, eg, my_table. Tables will be created automatically when proxy is started; data in tables is not preserved when proxy is restarted! You can add or remove new values from table dynamically at any moment with commands like:
- /opt/mtp_proxy/bin/mtp_proxy eval 'mtp_policy_table:add(my_table, tls_domain, "google.com").' to add
- /opt/mtp_proxy/bin/mtp_proxy eval 'mtp_policy_table:del(my_table, tls_domain, "google.com").' to remove

Some policy recipes / examples below

Limit max connections to proxy port from single IP

Here we allow maximum 100 concurrent connections from single IP to proxy port (as it was said earlier, it's not the same as 100 unique "users"! Each telegram client opens up to 8 connections; usually 3):

{mtproto_proxy,
 [
  {policy,
    [{max_connections, [port_name, client_ipv4], 100}]},
  {ports,
    <..>

Disallow connections from some IPs

{mtproto_proxy
 [
   {policy,
     [{not_in_table, client_ipv4, ip_blacklist}]},
   {ports,
     <..>

And then add IPs to blacklist with command:

/opt/mtp_proxy/bin/mtp_proxy eval '
mtp_policy_table:add(ip_blacklist, client_ipv4, "203.0.113.1").'

Remove from blacklist:

/opt/mtp_proxy/bin/mtp_proxy eval '
mtp_policy_table:del(ip_blacklist, client_ipv4, "203.0.113.1").'

Personal proxy / multi-secret proxy

We can limit number of connections with single fake-TLS domain and only allow connections with fake-TLS domains from whitelist.

{mtproto_proxy
 [
   {policy,
     [{max_connections, [port_name, tls_domain], 15},
      {in_table, tls_domain, customer_domains}]},
   {ports,
     <..>

Now we can assign each customer unique fake-TLS domain, eg, my-client1.example.com and give them unique TLS secret. Because we only allow 10 connections with single fake-TLS secret, they will not be able to share their credentials with others. To add client's fake domain to whitelist:

/opt/mtp_proxy/bin/mtp_proxy eval '
mtp_policy_table:add(customer_domains, tls_domain, "my-client1.example.com").'

And then use http://seriyps.ru/mtpgen.html to generate unique link for them. Be aware that domains table will be reset if proxy is restarted! Make sure you re-add them when proxy restarts (eg, via systemd hook script).

IPv6

Currently proxy only supports client connections via IPv6, but can only connect to Telegram servers using IPv4.

To enable IPv6, you should put IPv6 address in listen_ip config key. If you want proxy to accept clients on the same port with both IPv4 and IPv6, you should have 2 ports sections with the same port, secret and tag, but with different names and different listen_ip (one v4 and one v6):

 {mtproto_proxy,
  %% see src/mtproto_proxy.app.src for examples.
  [
   {ports,
    [#{name => mtp_handler_all_ipv4,
       listen_ip => "0.0.0.0",  % IPv4 address, eg 203.0.113.1
       port => 1443,
       secret => <<"d0d6e111bada5511fcce9584deadbeef">>,
       tag => <<"dcbe8f1493fa4cd9ab300891c0b5b326">>},
     #{name => mtp_handler_all_ipv6,
       listen_ip => "::",  % IPv6 address, eg "2001:db8:85a3::8a2e:370:7334"
       port => 1443,
       secret => <<"d0d6e111bada5511fcce9584deadbeef">>,
       tag => <<"dcbe8f1493fa4cd9ab300891c0b5b326">>}
    ]}
   ]},

 {lager,
<...>

Tune resource consumption

If your server have low amount of RAM, try to set

{upstream_socket_buffer_size, 5120},
{downstream_socket_buffer_size, 51200},
{replay_check_session_storage, off},
{init_timeout_sec, 10},
{hibernate_timeout_sec, 30},
{ready_timeout_sec, 120},  % close connection after 2min of inactivity

this may make proxy slower, it can start to consume bit more CPU, will be vulnerable to replay attacks, but will use less RAM. You should also avoid max_connections policy because it uses RAM to track connections.

If your server have lots of RAM, you can make it faster (users will get higher uppload/download speed), it will use less CPU and will be better protected from replay attacks, but will use more RAM:

{max_connections, 128000},
{upstream_socket_buffer_size, 20480},
{downstream_socket_buffer_size, 512000},
{replay_check_session_storage, on},
{replay_check_session_storage_opts,
  #{max_memory_mb => 2048,
    max_age_minutes => 1440}},

One more option to decrease CPU usage is to disable CRC32 checksum check:

{mtp_full_check_crc32, false},

Also, for highload setups it's recommended to increase sysctl parameters:

sudo sysctl net.ipv4.tcp_max_orphans=128000
sudo sysctl 'net.ipv4.tcp_mem=179200 256000 384000'

Values for tcp_mem are in pages. Size of one page can be found by getconf PAGESIZE and is most likely 4kb.

If you have installed proxy via Docker or use some NAT firewall settings, you may want to increase netfilter conntrack limits to be at least the max number of connections you expect:

sudo sysctl net.netfilter.nf_conntrack_max=128000

Helpers

Number of connections

/opt/mtp_proxy/bin/mtp_proxy eval 'lists:sum([proplists:get_value(all_connections, L) || {_, L} <- ranch:info()]).'

seriyps/mtproto_proxy

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