Licensing information about netfilter/iptables

As netfilter/iptables is increasingly used by commercial vendors as part of their network security products, we'd like to give some explanations on how to comply with the license terms of this software.

The target audience for this document is somebody who re-distributes any software published by the netfilter/iptables project, independent of the medium of distribution (cd-rom, floppy disk, firmware image in flash/rom, internet download, ...).

netfilter/iptables is, like the Linux operating system kernel itself, “free software”. Free refers to free as in freedom. It doesn't necessarily make a statement about the cost. Free does explicitly NOT mean “free of any obligations”.

As many free software, netfilter/iptables is licensed under the terms of the GNU General Public License (GPL), Version 2. You can find the full text of this license at http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt. There's also a comprehensive list of frequently asked questions available.

In any doubt, feel free to contact the netfilter core team at <coreteam@netfilter.org> BEFORE you ship any product containing our source code.

According to Section 1 of the GNU GPLv2, you have the following obligations when distributing the original source code as published by the netfilter/iptables project:

According to Section 2 of the GNU GPLv2, you have the following obligations when distributing or publishing modified versions of the source code:

According to section 3 of the GNU GPLv2, when distributing or publishing either original or modified version of the program, you have to fulfill all the obligations of Section 1 and 2, plus one out of the two possible options:

Let's assume you are a vendor that sells embedded firewalling devices, using any of the netfilter/iptables code. Let's assume you are shipping this device with pre-installed object code of the software (sometimes referred to as firmware), but also offer software updates via the internet.

Because of your specific needs, you had to modify parts of the original netfilter/iptables code to make it fit your requirements.

The GPL gives you two different ways of complying with the license. You can chose between both. However, the netfilter project prefers the option described first in this document:

netfilter/iptables is a community based effort. This means that if it weren't for volunteers contributing source code to the project, it wouldn't exist and you wouldn't be able to build products based on it.

So as long as you want to continue selling netfilter/iptables products, it is in your own vital interest that the netfilter/iptables project flourishes. Contributions to the project are the most important part in the development of our project.

Vendors are welcome to contribute their modifications and/or new features back to the project. This way we can consider to include them into one of our next releases, and thus increasing the value of our software.

There are lots of other ways how you can support and encourage further development of the netfilter/iptables software. Possible options include:

If you are interested in supporting the netfilter/iptables project in any way, maybe even one not listed above, please don't hesitate to contact us at <coreteam@netfilter.org>.

Netfilter provides useful information regarding the licensing terms for netfilter/iptables here. The netfilter community wants to help users to comply with the GPL.

Yes. The core team members of the netfilter project have officially endorsed and support "The Principles of Community-Oriented GPL Enforcement" in this public statement.

Although core team members of the netfilter project support "The Principles of Community-Oriented GPL Enforcement", Patrick McHardy, unfortunately, did not join with us to sign these principles. We have been told that Patrick McHardy has undertaken compliance actions relating to netfilter code that are inconsistent with these community norms, and we fear that the enforcement actions of Patrick McHardy have caused considerable harm to the reputation of the netfilter project. There are serious allegations that his GPL enforcement activities are prioritizing personal financial gain over compliance. We contacted him to address these allegations many times, however, we got no response from him so far. As a result, the netfilter community has, in fact, suspended Patrick McHardy from the core team until he undertakes a commitment to join with the rest of the netfilter core team in supporting the principles.

We cannot provide any legal advice, but we want to share our experience in this field and provide the following references: