link

README

Overview

Link is a powerful TCP connection management tool that simplifies NAT traversal, TCP forwarding and more. By seamlessly integrating three distinct running modes within a single binary file, Link bridges the gap between different network environments, redirecting services and handling TCP connections seamlessly, ensuring reliable network connectivity and ideal network environment. Also with highly integrated authorization handling, Link empowers you to efficiently manage user permissions and establish uninterrupted data flow, ensuring that sensitive resources remain protected while applications maintain high performance and responsiveness.

Features

• Unified Operation: Link can function as a server, client, or broker, three roles from a single executable file.

• Authorization Handling: By IP address handling, Link ensures only authorized users gain access to sensitive resources.

• Automated Certificate: Uses Certmagic for seamless, automatic certificate issuance and renewal with domain available.

• In-Memory Certificate: Provides a self-signed HTTPS certificate with a one-year validity, stored entirely in memory.

• Auto Reconnection: Providing robust short-term reconnection capabilities, ensuring uninterrupted service.

• Connection Updates: In scenarios where connection is interrupted, Link supports real-time connection updates.

• Service Forwarding: Efficiently manage and redirect TCP connections from one service to entrypoints everywhere.

Usage

To run the program, provide a URL specifying the mode and connection addresses. The URL format is as follows:

server://linkAddr/targetAddr
client://linkAddr/targetAddr
broker://linkAddr/targetAddr

Note that only server and broker mode support authorization Handling, which you can just add auth entry after #. For example:

server://linkAddr/targetAddr#authScheme://authAddr/secretPath
broker://linkAddr/targetAddr#authScheme://authAddr/secretPath

• authScheme: The option allows you to choose between using HTTP or HTTPS.
• authAddr: The server address and port designated for authorization handling.
• secretPath: The secret endpoint for processing authorization requests.

Server Mode

• linkAddr: The address for accepting client connections. For example, :10101.
• targetAddr: The address for listening to external connections. For example, :10022.

Run as Server

./link server://:10101/:10022

• This command will listen for client connections on port 10101 , listen and forward data to port 10022.

Run as Server with authorization

./link server://:10101/:10022#https://hostname:8443/server

• The server handles authorization at https://hostname:8443/server, on your visit and your IP logged.
• The server will listen for client connections on port 10101 , listen and forward data to port 10022.

Client Mode

• linkAddr: The address of the server to connect to. For example, server_ip:10101.
• targetAddr: The address of the target service to connect to. For example, 127.0.0.1:22.

Run as Client

./link client://server_hostname_or_IP:10101/127.0.0.1:22

• This command will establish link with server_hostname_or_IP:10101 , connect and forward data to 127.0.0.1:22.

Broker Mode

• linkAddr: The address for accepting client connections. For example, :10101.
• targetAddr: The address of the target service to connect to. For example, 127.0.0.1:22.

Run as Broker

./link broker://:10101/127.0.0.1:22

• This command will listen for client connections on port 10101 , connect and forward data to 127.0.0.1:22.

Run as Broker with authorization

./link broker://:10101/127.0.0.1:22#https://hostname:8443/broker

• The server handles authorization at https://hostname:8443/broker, on your visit and your IP logged.
• The server will listen for client connections on port 10101 , connect and forward data to 127.0.0.1:22.

Container Usage

You can also run Link using a Docker container. The image is available at ghcr.io/raymondragon/link.

To run the container in server mode with or without authorization:

docker run --rm ghcr.io/raymondragon/link server://:10101/:10022#https://hostname:8443/server

docker run --rm ghcr.io/raymondragon/link server://:10101/:10022

To run the container in client mode:

docker run --rm ghcr.io/raymondragon/link client://server_hostname_or_IP:10101/127.0.0.1:22

To run the container in server mode with or without authorization:

docker run --rm ghcr.io/raymondragon/link broker://:10101/127.0.0.1:22#https://hostname:8443/broker

docker run --rm ghcr.io/raymondragon/link broker://:10101/127.0.0.1:22

License

This project is licensed under the MIT License. See the LICENSE file for details.