BusyBox is licensed under the GNU General Public License , which is generally just abbreviated simply as the GPL license, or just the GPL. Anyone thinking of shipping BusyBox as part of a product 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
to be sure you (and your lawyers) fully understand them.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 BusyBox Hall of Shame page. You will be able to sleep peacefully at night knowing you have fulfilled all your licensing obligations.
If you distribute a product, it should either be accompanied by full source for all GPL'd products (including BusyBox) and/or a written offer 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 mandatory.
Accompanied by source 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.
A written offer generally means that somewhere in the docs for your product, you write something like
The GPL source code contained in this product is available as a free download from http://blah.blah.blah/Or you can offer source by writing somewhere in the docs for your product something like
If you would like a copy of the GPL source code in this product on a CD, please send $9.99 to <address> for the costs of preparing and mailing a CD to you.
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 must either make source available online (i.e. accompanied by source) and/or inform those downloading firmware updates of their right to obtain source (i.e. a written offer). Failure to do so is a violation of your licensing obligations.
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 text of GPL. 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.
These days, Linksys 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 distributing the firmware for their WRT54G Router. Following their example would be a fine way to ensure you have fulfilled your licensing obligations.