IPTables Port Manager

iptables_port_manager is a project that facilitates the dynamic management of port forwarding using iptables and systemd on a Linux system. It is particularly useful for handling a large number of backtunnels from local VMs over NAT to a remote VPS with a public IP, without needing to keep all of them open all the time. The ports are opened only when needed and closed automatically after an SSH connection is established.

Features

• Automatically opens and closes ports using iptables.
• Operates as a systemd service running an infinite bash loop.
• Useful for managing backtunnels with minimal open ports.

Prerequisites

• Linux system with root privileges.
• iptables installed on the system.
• systemd installed and running.

Installation

1. Clone the Repository:

   git clone https://github.com/uxumax/iptables_port_manager.git
   cd iptables_port_manager

2. Run the Installation Script: The install.sh script will copy necessary files, set appropriate permissions, and enable and start the systemd service.

   sudo ./install.sh

Usage

Once installed, the service will automatically start and run the port_manager.sh script in an infinite loop. This script reads port numbers from /tmp/ports_to_open.list, opens them, and then closes them after a set time delay.

To open a port:

• Add the port number to the /tmp/ports_to_open.list file.

Example:

echo "2222" >> /tmp/ports_to_open.list

The service will automatically detect the new port in the list, open it, and close it after a delay.

Better way set 600 privileges to this file but this depends on your case:

chmod 600 /tmp/ports_to_open.list

You can change path ports_to_open.list to any place. Just change PORTS_FILE value in ./port_manager.sh script if before run installation or in /usr/sbin/port_manager.sh if already installed:

PORTS_FILE="your/new/better/place/ports_to_open.list"

Related projects

• ossh - simple SSH wrapper that allows you to run custom scripts before and after an SSH connection is established. You can open a port by simply adding a command to ~/.ssh/scripts/before_established.sh that adds the port number to $PORTS_FILE on your server.

License

MIT License

Contributing

Feel free to fork the project and submit pull requests. For major changes, please open an issue to discuss what you would like to change.

Author

• uxumax