tun2proxy/README.md

# tun2proxy
Tunnel TCP traffic through SOCKS5 or HTTP on Linux.

**Error handling incomplete and too restrictive.**

## Build
Clone the repository and `cd` into the project folder. Then run the following:
```
cargo build --release
```

## Setup
A standard setup, which would route all traffic from your system through the tunnel interface, could look as follows:
```shell
# The proxy type can be either SOCKS5 or HTTP.
PROXY_TYPE=SOCKS5
PROXY_IP=1.2.3.4
PROXY_PORT=1080

# Create a tunnel interface named tun0 which your user can bind to,
# so we don't need to run tun2proxy as root.
sudo ip tuntap add name tun0 mode tun user $USER
sudo ip link set tun0 up

# To prevent a routing loop, we add a route to the proxy server that behaves
# like the default route.
sudo ip route add "$PROXY_IP" $(ip route | grep '^default' | cut -d ' ' -f 2-)

# Route all your traffic through tun0 without interfering with the default route.
sudo ip route add 128.0.0.0/1 dev tun0
sudo ip route add 0.0.0.0/1 dev tun0

./target/release/tun2proxy --tun tun0 --proxy "$PROXY_TYPE://$PROXY_IP:$PROXY_PORT"
```

Note that if you paste these commands into a shell script, which you then run with `sudo`, you might want to replace
`$USER` with `$SUDO_USER`.

For DNS to work, you might need an additional tool like [dnsproxy](https://github.com/AdguardTeam/dnsproxy) that is
configured to listen on a local UDP port and communicates with the upstream DNS server via TCP.

When you terminate this program and want to eliminate the impact caused by the above several commands,
you can execute the following command. The routes will be automatically deleted with the tunnel device.
```shell
sudo ip link del tun0
```

## CLI
```
Tunnel interface to proxy.

Usage: tun2proxy [OPTIONS] --proxy <URL>

Options:
  -t, --tun <name>   Name of the tun interface [default: tun0]
  -p, --proxy <URL>  The proxy URL in the form proto://[username[:password]@]host:port
  -h, --help         Print help
  -V, --version      Print version
```
Currently, tun2proxy supports two proxy protocols: HTTP and SOCKS5. A proxy is supplied to the `--proxy` argument in the
URL format. For example, an HTTP proxy at `1.2.3.4:3128` with a username of `john.doe` and a password of `secret` is
supplied as `--proxy http://john.doe:secret@1.2.3.4:3128`. This works analogously to curl's `--proxy` argument.

## TODO
- UDP support for SOCKS
- Virtual DNS