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Knowledge document #894

Setting up automatic port sharing

By default, the FRITZ!Box's firewall blocks all incoming connections from the internet. If some of the internet applications (for example chat software, online games, file-sharing software) you use require port sharings for incoming connections from the internet, you can configure the FRITZ!Box so that the network device on which the internet application is running can set up the necessary port sharing settings by itself if required.

The port sharings are only set up for the period of time during which the application requires them, and then the FRITZ!Box disables them again.

Requirements / Restrictions

  • The FRITZ!Box must establish its own connection to the internet through a modem (for example a DSL or cable modem).
  • For IPv4 internet access, the FRITZ!Box must obtain a public IPv4 address from the internet service provider.
  • For IPv6 internet access, the FRITZ!Box must obtain an IPv6 address from the internet service provider.

Note:All instructions on configuration and settings given in this guide refer to the latest FRITZ!OS for the FRITZ!Box.

1 Configuring the FRITZ!Box for automatic port sharing

  1. Click "Home Network" in the FRITZ!Box user interface.
  2. Click "Network" in the "Home Network" menu.
  3. Click on the "Network Connections" tab.
  4. Click the (Edit) button next to the device you want to configure.
  5. Enable the option "Permit independent port sharing for this device".
  6. Click "OK" to save the settings.

2 Configuring the application for automatic port sharing

  1. Configure the application so that it uses PCP or UPnP. Refer to the manufacturer for information on how to set it up, for example consult the manual.

3 Configuring the computer's firewall

If the application is installed on a computer with its own firewall (for example Windows firewall), the firewall must also be configured:

Important:If you allow devices to set up port sharing themselves, malware could also set up port sharing on these devices and thus bypass the FRITZ!Box's firewall. You should therefore set up a firewall on these devices for security reasons.

  1. Configure the computer's firewall according to the manufacturer's instructions so that the server service or application can be accessed from the FRITZ!Box home network.

Now applications can automatically open the required ports in the FRITZ!Box.

Ports currently enabled for port sharing are shown in the detailed information on the respective network device under "Home Network > Mesh" in the FRITZ!Box user interface. You can also find an overview of opened ports under "Internet > Permit Access" and "Diagnostics > Security" in the user interface.