A modern, simple TCP tunnel in Rust that exposes local ports to a remote server, bypassing standard NAT connection firewalls. **That's all it does: no more, and no less.**
Like [localtunnel](https://github.com/localtunnel/localtunnel) and [ngrok](https://ngrok.io/), except `bore` is intended to be a highly efficient, unopinionated tool for forwarding TCP traffic that is simple to install and easy to self-host, with no frills attached.
You can forward a port on your local machine by using the `bore local` command. This takes a positional argument, the local port to forward, as well as a mandatory `--to` option, which specifies the address of the remote server.
```shell
bore local 5000 --to bore.pub
```
You can optionally pass in a `--port` option to pick a specific port on the remote to expose, although the command will fail if this port is not available.
The full options are shown below.
```shell
bore-local 0.1.0
Starts a local proxy to the remote server
USAGE:
bore local [OPTIONS] --to <TO><LOCAL_PORT>
ARGS:
<LOCAL_PORT> The local port to listen on
OPTIONS:
-h, --help Print help information
-p, --port <PORT> Optional port on the remote server to select [default: 0]
-t, --to <TO> Address of the remote server to expose local ports to
As mentioned in the startup instructions, there is an public instance of the `bore` server running at `bore.pub`. However, if you want to self-host `bore` on your own network, you can do so with the following command:
```shell
bore server
```
That's all it takes! After the server starts running at a given address, you can then update the `bore local` command with option `--to <ADDRESS>` to forward a local port to this remote server.
There is an implicit _control port_ at `7835`, used for creating new connections on demand. At initialization, the client sends a "Hello" message to the server on the TCP control port, asking to proxy a selected remote port. The server then responds with an acknowledgement and begins listening for external TCP connections.
Whenever the server obtains a connection on the remote port, it generates a secure [UUID](https://en.wikipedia.org/wiki/Universally_unique_identifier) for that connection and sends it back to the client. The client then opens a separate TCP stream to the server and sends an "Accept" message containing the UUID on that stream. The server then proxies the two connections between each other.
For correctness reasons and to avoid memory leaks, incoming connections are only stored by the server for up to 10 seconds before being discarded if the client does not accept them.
Created by Eric Zhang ([@ekzhang1](https://twitter.com/ekzhang1)). Licensed under the [MIT license](LICENSE).
The author would like to thank the contributors and maintainers of the [Tokio](https://tokio.rs/) project for making it possible to write ergonomic and efficient network services in Rust.
