rstun

A secure UDP tunnel written in Rust.

rstun builds on Quinn, which is an implementation of the IETF QUIC transport protocol.

rstun consists of two binaries, rstunc for client and rstund for server. rstund accepts connections from rstunc.

rstunc connects to the server to build a secure tunnel to allow data to be exchanged between two ends, it initiates the connection in one of two modes:

• The IN mode for exposing a local port to the internet through the server.
• The OUT mode for securing data going out from local to the internet through the server.

All traffic going through the tunnel is secured by the builtin TLS layer of the QUIC protocol, when the negotiation of the connection completes and a tunnel is built, QUIC streams can be initiated from both ends, for the OUT mode, streams are initiated from the client, and for the IN mode, it is just the opposite.

Usage

• Start the server

rstund \
  --addr 0.0.0.0:6060 \
  --upstreams 8800 \
  --password 123456 \
  --cert path/to/cert.der \
  --key path/to/key.der

• addr specifies the ip:port that the server is listening on.
• upstreams specifies a TCP port which traffic from the client through the tunnel will be relayed to on the server, this is applicable for OUT mode tunnels only, multiple comma-separated upstreams can be set. Note this argument is optional, if it is not specified, all open ports of the server are exposed to the clients through the tunnel. So make sure to specify upstreams if exposing all open ports of the server is not desired.
• password, password of the server, the client rstunc is required to send this password to successfully build a tunnel with the server.
• cert and key are certificate and private key for the domain of the server, self-signed certificate is allowed, but you will have to connect to the server using IP address and the certificate will also be required by rstunc for verification in this case (see below). Anyway, getting a certificate for your domain from a trusted CA and connecting to the server using domain name is always recommended. Note cert and key are optional, if they are not specified, the domain localhost is assumed and a self-signed certificate is generated on the fly, but this is for TEST only, Man-In-The-Middle attack can occur with such setting, so make sure it is only used for TEST!

• Start the client

rstunc
  --mode OUT \
  --server-addr 1.2.3.4:6060 \
  --password 123456 \
  --cert path/to/cert.der \
  --addr-mapping 0.0.0.0:9900^8800

• mode here is OUT, for securing traffic from local to the server through the tunnel.
• server-addr, domain name or IP address of the server.
• password, same as that for the server.
• cert, see explanation above for rstund. Note this is also optional if connecting to the server with a domain name, or the server rstund runs with an auto-generated self-signed certificate (see the TEST example below).
• addr-mapping is an address mapping between two ip:port pairs separated by the ^ character, the format is [ip:]port^[ip:]port, in the example above, a local port 9900 is mapped to the remote port 8800 of the 1.2.3.4 server that runs rstund. i.e. all traffic from the local port 9900 will be forwarded to the remote port 8800 through the tunnel. addr-mapping also supports the following 3 combinations:
  • ANY^8000 for not explicitly specifying a port for the local access server (the client), the bound port will be printed to the terminal as following [TunnelOut] access server bound to: 0.0.0.0:60001, in which 60001 is a random port.
  • 8000^ANY for not explicitly specifying a port to bind with the remote server, the server decides that port, so it depends on that the server is started with explicitly setting the --upstreams option.
  • ANY^ANY both the cases of the settings above.

• Simple TEST example

The following commands run a server, then a client that connects to the server in their simplest ways:

# Remote: run the server with auto-generated self-signed certificate
rstund -a 9000 -p 1234

# Local: connect to the server (127.0.0.1:9000) and bind the local port 9900 to remote port 8800
rstunc -m OUT -r 127.0.0.1:9000 -p 1234 -a 0.0.0.0:9900^8800

• Complete options for rstund

Usage: rstund [OPTIONS] --password <PASSWORD>

Options:
  -a, --addr <ADDR>
          Address ([ip:]port pair) to listen on, a random port will be chosen and binding to all network interfaces (0.0.0.0) if empty [default: ]
  -u, --upstreams <UPSTREAMS>
          Exposed upstreams (comma separated) as the receiving end of the tunnel, e.g. -u [ip:]port, The entire local network is exposed through the tunnel if empty
  -p, --password <PASSWORD>
          Password of the tunnel server
  -c, --cert <CERT>
          Path to the certificate file, if empty, a self-signed certificate with the domain "localhost" will be used [default: ]
  -k, --key <KEY>
          Path to the key file, can be empty if no cert is provided [default: ]
  -t, --threads <THREADS>
          Threads to run async tasks [default: 0]
  -w, --max-idle-timeout-ms <MAX_IDLE_TIMEOUT_MS>
          Max idle timeout for the connection [default: 40000]
  -l, --loglevel <LOGLEVEL>
          [default: I] [possible values: T, D, I, W, E]
  -h, --help
          Print help
  -V, --version
          Print version

• Complete options for rstunc

Usage: rstunc [OPTIONS] --mode <MODE> --server-addr <SERVER_ADDR> --password <PASSWORD> --addr-mapping <ADDR_MAPPING>

Options:
  -m, --mode <MODE>
          Create a tunnel running in IN or OUT mode [possible values: IN, OUT]
  -r, --server-addr <SERVER_ADDR>
          Address (<domain:ip>[:port] pair) of rstund, default port is 3515
  -p, --password <PASSWORD>
          Password to connect with rstund
  -a, --addr-mapping <ADDR_MAPPING>
          LOCAL and REMOTE mapping in [ip:]port^[ip:]port format,
          e.g. 8080^0.0.0.0:9090 `ANY^8000` for not explicitly specifying a port
          for the local access server (the client) `8000^ANY` for not explicitly
          specifying a port to bind with the remote server, the server decides that
          port, so it depends on that the server is started with explicitly setting
          the `--upstreams` option. `ANY^ANY` both the cases of the settings above
  -c, --cert <CERT>
          Path to the certificate file, only needed for self signed certificate [default: ]
  -e, --cipher <CIPHER>
          Preferred cipher suite [default: chacha20-poly1305] [possible values: chacha20-poly1305, aes-256-gcm, aes-128-gcm]
  -t, --threads <THREADS>
          Threads to run async tasks [default: 0]
  -w, --wait-before-retry-ms <WAIT_BEFORE_RETRY_MS>
          Wait time before trying [default: 5000]
  -i, --max-idle-timeout-ms <MAX_IDLE_TIMEOUT_MS>
          Max idle timeout for the connection [default: 30000]
  -l, --loglevel <LOGLEVEL>
          Log level [default: I] [possible values: T, D, I, W, E]
  -h, --help
          Print help
  -V, --version
          Print version

License

This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.