gsproxy/README.md

# GSproxy

GSproxy is a standalone Perl tool that reads a CSV list of remote targets and keeps a working SOCKS proxy alive for each of them. It brings up remote SOCKS servers over an MCP shell bridge, starts local gs-netcat SOCKS clients, watches every proxy, and exposes a single gateway SOCKS port that always points at the first healthy proxy.

## Overview

The tool turns a list of `endpoint,secret,port` rows into a self-healing set of SOCKS proxies. For each row it does three things:

- Brings up a remote SOCKS server through an MCP `Tools_Shell_Command` call, using a gs-netcat listener wrapped to look like `python`.
- Starts a local gs-netcat SOCKS client bound to `127.0.0.1` on the row's port.
- Monitors the local SOCKS proxy and logs every status change.

It then listens on a gateway SOCKS port and relays each incoming connection to the first proxy that is currently alive.

The whole tool is written with core Perl modules only, so it runs without extra installs.

## Features

- CSV driven config, one proxy per row.
- Remote bring-up through an MCP shell call, reusing the gs-netcat listener command shape.
- Local gs-netcat SOCKS client launched per row.
- Continuous monitoring with configurable interval and per-check timeout.
- Automatic re-bring-up of dead proxies in the background.
- A gateway SOCKS port that follows the first alive proxy.
- Daemon mode with pidfile, status, and stop commands.
- Remote and local teardown that kills leftover gs-netcat processes.
- Offline self-tests that cover config parsing, command building, and the SOCKS handshake.

## Requirements

- Perl 5 with the core modules `Getopt::Long`, `IO::Socket::INET`, `IO::Select`, `POSIX`, `HTTP::Tiny`, `JSON::PP`, `Time::HiRes`, `File::Spec`, `Errno`, and `File::Basename`.
- The `gs-netcat` binary in `PATH`, or a path supplied with `--gs-netcat`.
- Network access from the MCP endpoint so the remote bring-up command can download and run gs-netcat.
- A reachable MCP endpoint that exposes the `Tools_Shell_Command` tool.

## Installation

- Copy `gsproxy.pl` somewhere on the host and make it executable with `chmod +x gsproxy.pl`.
- Make sure `gs-netcat` is installed and on the `PATH`.
- Create a `gsproxy.csv` next to the script, or point `--config` at another file.

## Configuration

The config file is CSV. Each non-empty, non-comment line has the form:

```
endpoint,secret,port[,label]
```

- `endpoint` is the base URL of the MCP server that exposes `Tools_Shell_Command`.
- `secret` is the gs-netcat shared secret used by both the remote listener and the local client.
- `port` is the local SOCKS port for that row. It must be a number from 1 to 65535.
- `label` is an optional friendly name. When missing it defaults to `row` plus the line number.

Blank lines and lines starting with `#` are ignored. A header line such as `endpoint,secret,port,label` is detected and skipped when the third field is not a number. Invalid rows are reported on standard error and skipped.

Example:

```
endpoint,secret,port,label
https://mcp.example.org,sekret123,20001,alpha
https://mcp.other.org,topsecret9,20002,beta
```

The `endpoint` may be a base URL or a full MCP URL. If it does not already end in `/gradio_api/mcp` or `/mcp`, the value of `--mcp-path` is appended.

## Usage

Run the tool as a daemon:

```
./gsproxy.pl
```

Run one monitor pass and exit:

```
./gsproxy.pl --once
```

Run in the foreground:

```
./gsproxy.pl --no-daemon
```

## Options

The script accepts these command line options:

- `--config FILE` sets the CSV config path. The default is `gsproxy.csv` next to the script.
- `--gateway-port PORT` sets the gateway SOCKS port. The default is `1080`.
- `--bind ADDR` sets the address the gateway listens on. The default is `0.0.0.0`.
- `--interval SEC` sets the monitor interval in seconds. The default is `30`.
- `--timeout SEC` sets the per-check timeout in seconds. The default is `10`.
- `--mcp-timeout SEC` sets the MCP shell command timeout in seconds. The default is `60`.
- `--test-host HOST` sets the host probed through each SOCKS proxy. The default is `www.google.com`.
- `--test-port PORT` sets the port probed through each SOCKS proxy. The default is `443`.
- `--workdir DIR` sets the remote working directory for the MCP call. The default is `.`.
- `--gs-netcat PATH` sets the gs-netcat binary. The default is `gs-netcat` from `PATH`.
- `--log FILE` sets the log file. The default is `gsproxy.log` next to the script.
- `--pidfile FILE` sets the pidfile. The default is `gsproxy.pid` next to the script.
- `--state FILE` sets the runtime state file. The default is `gsproxy.state` next to the script.
- `--insecure` disables TLS certificate checks for the MCP endpoint.
- `--no-mcp` skips the remote MCP bring-up call.
- `--no-local` skips the local gs-netcat client start.
- `--no-bringup` runs monitor only and never restarts proxies.
- `--no-daemon` runs in the foreground.
- `--once` runs one monitor pass and then exits.
- `--list` parses the config, prints the rows, and exits.
- `--status` reports whether the daemon is running.
- `--stop` stops a running daemon and tears down proxies.
- `--selftest` runs the offline self-tests.
- `-h, --help` shows the help text.

The `--daemon` option is a negatable boolean and defaults to on. `--verbose` and `-v` increase logging to standard error.

## How it works

gsproxy has four moving parts: the remote bring-up, the local client, the monitor, and the gateway.

- Remote bring-up downloads a gs-netcat build with `curl`, unpacks it, and runs a gs-netcat listener with `-lSD -s SECRET`. The listening process is renamed to `python` so it blends into the host.
- The local client runs `gs-netcat -D -p PORT -s SECRET`, which opens a SOCKS listener on `127.0.0.1` at the row's port.
- The monitor performs a full SOCKS5 handshake against each local port, testing a real CONNECT to a probe host and port. A passing handshake marks the proxy alive.
- The gateway accepts SOCKS5 connections on `--bind:--gateway-port` and relays them to the first alive proxy listed in the state file.

### MCP bring-up

The remote call is an MCP JSON-RPC exchange over HTTP. The script sends an `initialize` request, captures the `Mcp-Session-Id` header, sends the `notifications/initialized` notification, then calls `tools/call` with the name `Tools_Shell_Command`. Responses may be plain JSON or server-sent events, so the body is parsed for the last `data:` line before decoding. Requests are retried up to three times on transport failures.

### Monitoring and state

On every interval the monitor checks each proxy, logs only status changes, and writes the list of alive ports to the state file. The first alive port from that list is the current gateway target. When a proxy is found dead, the tool forks a background bring-up unless `--no-bringup` is set. In `--once` mode the bring-up runs inline instead of forking.

### Gateway relay

The gateway listens, forks per connection, and reads the target port from the state file. It opens a TCP connection to that port and copies bytes in both directions with `IO::Select`, shutting down each direction as its side closes. If the state file has no valid port, the connection is dropped.

### Teardown

Stopping the tool cleans up both sides. Locally it scans `/proc` for gs-netcat processes that match the `-D -p PORT` shape and sends them `TERM`. Remotely it runs a shell command over MCP that scans `/proc` for processes whose environment contains `GSOCKET_ARGS=-lSD -s SECRET` and kills them.

## Command reference

- Start as a daemon: `./gsproxy.pl`
- Start and stop: `./gsproxy.pl --stop`
- Check status: `./gsproxy.pl --status`
- List config rows: `./gsproxy.pl --list`
- One pass, foreground: `./gsproxy.pl --once --no-daemon`
- Run self-tests: `./gsproxy.pl --selftest`

## Files

- `gsproxy.csv` is the default config file.
- `gsproxy.log` is the append-only log, one UTC-stamped line per event.
- `gsproxy.pid` holds the daemon and gateway process ids.
- `gsproxy.state` holds the first alive port on the first line and all alive ports on the second.

## Logging

Every event is written with a UTC timestamp in the form `[YYYY-MM-DDTHH:MM:SSZ] message`. Bring-up, MCP results, status changes, gateway startup, and teardown are all logged. The log is appended, never truncated, so it grows over time. With `--verbose`, log lines are also printed to standard error.

## Gateway behavior

- The gateway always targets the first alive proxy in listing order.
- It re-reads the state file on every new connection, so failover is immediate.
- A dead or missing target port causes the connection to be dropped without reply.
- Each connection is handled by a forked child, keeping the listener responsive.

## Self-tests

The `--selftest` mode runs offline checks and prints `PASS` or `FAIL` per case. It writes a temporary CSV, a temporary state file, and a temporary log under `/tmp`. It covers config parsing, command string quoting, gs-netcat process discovery, live and dead SOCKS detection, and a full gateway relay against a fake SOCKS server. It exits non-zero if any check fails.

## Security notes

- Secrets are masked in logs and list output, so only the first two characters appear.
- The remote process is deliberately renamed to `python` to hide on the target host.
- The `--insecure` flag turns off TLS verification and should be used only when the MCP endpoint is trusted.
- The gateway binds to `0.0.0.0` by default. Restrict `--bind` if the host should not expose the proxy to the network.
- Anyone who can reach the gateway SOCKS port can route through the current proxy, so the port should be firewalled.

## Troubleshooting

- If the script reports no usable rows, check that the CSV has valid `endpoint,secret,port` fields and a numeric port.
- If the daemon will not start, run `--status` to see whether it is already running, then use `--stop` first.
- If MCP bring-up fails, confirm the endpoint exposes `Tools_Shell_Command` and try `--insecure` only if the certificate is the problem.
- If no proxy becomes alive, run `--list` to confirm the rows and check that `gs-netcat` is on the `PATH`.
- If the gateway has no target, watch the log for `SOCKS ... is dead` lines to see which proxies are failing.

## Credits

Created by Luxferre in 2026, released into the public domain with no warranties.