# Managing open ports

## Manually opening and closing ports

You can use the following to expose ports on your instances, replacing `<port_number>` with the port number you want to forward to your instance's public IP:

```sh
sudo nohup foundrypf <port_number> >/dev/null 2>&1 &
```

This will start a process that maintains the open port. You can omit `nohup` to run it in the foreground.

You can close the port with the following command, replacing `<port_number>` with the port number you want to close:&#x20;

```sh
sudo foundrypf -d <port_number>
```

## Creating a systemd service to expose ports

If you want to ensure the port forwarding is kept running in the background persistently even after a system reboot or in the case that the process fails in the background due to network blips, you can create a systemd service for it.

Open a new service file using a text editor (in this case, nano):

```bash
sudo nano /etc/systemd/system/examplefoundry.service
```

Add the following content to the service file:

```
[Unit]  
Description=Foundry Port Forwarding Service  
After=network.target
Wants=network-online.target

[Service]  
Type=simple  
User=root  
ExecStart=/usr/local/bin/foundrypf <port_number>  
Restart=always  
RestartSec=3

[Install]  
WantedBy=multi-user.target
```

Again, replace `<port_number>` with the port you want to keep forwarded persistently.

```bash
sudo systemctl daemon-reload  
sudo systemctl enable examplefoundry  
sudo systemctl start examplefoundry
```

Now, the `foundrypf` script will run as a service, and the specified port will be forwarded persistently. Adjust the `<port_number>` and service file name if you wish to set up multiple such services for different ports.

Note that lower-number ports are currently not supported on `foundrypf`. We recommend running applications on higher-number ports.


---

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