busybox/docs/busybox.net/license.html

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<h3>The GPL BusyBox license</h3>

There has been some confusion in the past as to exactly what is
required to safely distribute GPL'd software such as BusyBox as
part of a product.  To ensure that there is no confusion
whatsoever, this page attempts to summarize what you should do to
ensure you do not accidentally violate the law.

<p>

<p>

BusyBox is licensed under the GNU General Public License , which
is generally just abbreviated simply as the GPL license, or
just the GPL.  <a href="/products.html">Anyone thinking of shipping
BusyBox as part of a product</a> should be familiar with the
licensing terms under which they are allowed to use and
distribute BusyBox.  You are advised to take a look over the

<ul>
<li><a href="http://www.gnu.org/licenses/gpl.html">full text of
the GNU General Public License</a>, and
<li><a href="http://www.gnu.org/licenses/gpl-faq.html">
Frequently Asked Questions about the GNU GPL</a>
</ul>
to be sure you (and your lawyers) fully understand them.

<p>

The following is a quick summary for the impatient.  If you
carefully follow these steps, it will ensure that you are 100%
authorized to ship BusyBox with your product, and have no reason
to worry about lawsuits or being listed on the <a
href="/shame.html">BusyBox Hall of Shame</a> page.  You will be
able to sleep peacefully at night knowing you have fulfilled all
your licensing obligations.

<p>

If you distribute a product, it should either be accompanied by
<b>full source for all GPL'd products</b> (including BusyBox)
and/or a <b>written offer</b> to supply the source for all
GPL'd products for the cost of shipping and handling.  The source
has to be in its preferred machine readable form, so you cannot
encrypt or obfuscate it.  You are not required to provide full
source for all the closed source applications that happen to be
part of the system with BusyBox, though you can certainly do so
if you feel like it.  But providing source for the GPL licensed
applications such as BusyBox is manditory.

<p>

<b>Accompanied by source</b> generally means you place the full
source code for all GPL'd products such as BusyBox on a driver CD
somewhere.  Full source code includes the BusyBox ".config" file
used when your shipping BusyBox binary was compiled.

<p>

<b>A written offer</b> generally means that somewhere in the
docs for your product, you write something like

<blockquote>
The GPL source code contained in this product is available as a
free download from http://blah.blah.blah/
</blockquote>
Or you can offer source by writing
somewhere in the docs for your product something like
<blockquote>
If you would like a copy of the GPL source code in this product
on a CD, please send $9.99 to &lt;address&gt; for the costs of
preparing and mailing a CD to you.
</blockquote>
<p>

Keep in mind though that if you distribute GPL'd binaries online
(as is often done when supplying firmware updates), it is highly
recommended that you make the corresponding source available online
at the same place.  Regardless, you <b>must</b> either make source
available online (i.e. <b>accompanied by source</b>) and/or inform
those downloading firmware updates of their right to obtain source
(i.e. <b>a written offer</b>).  Failure to do so is a violation of
your licensing obligations.


<p>

Some people have the mistaken understanding that if they use unmodified
GPL'd source code, they do not need to distribute anything.  This belief
is not correct, and is not supported by the
<a href="http://www.gnu.org/licenses/gpl.html">text of GPL</a>.
Please do re-read it -- you will find there is no such provision.
If you distribute any GPL'd binaries, you must also make source available
as discussed on this webpage.

<p>

These days, <a href="http://www.linksys.com/">Linksys</a> is
doing a good job at complying with the GPL, they get to be an
example of how to do things right.  Please take a moment and
check out what they do with
<a href="http://www.linksys.com/download/firmware.asp?fwid=178">
distributing the firmware for their WRT54G Router.</a>
Following their example would be a fine way to ensure you have
fulfilled your licensing obligations.


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