[Xorp-users] Question regarding GPL license

[Ben Greear]

On 07/15/2012 08:22 AM, 张东亚 wrote:
> Hi Ben Greear,
>    This weekend I found the 1.0 version source code released by pica8,
> after some quick glance, I noted that in order to implement their CLI
> shell, they inherit XORP shell class and implement a new CLI shell.
>    Then I am a little confused regarding in your letter about that it
> can be perfectly legal to use proprietary modules in XORP , because
> CLI related source code is released under GPL, If I (not pica8) want
> to build some proprietary module and want implement a different but
> like XORP CLI shell, the only way I can do is release the CLI shell
> under GPL ? (Maybe the CLI shell is customed and doesn't mean too much
> to be released under GPL).
>    Hoping for reply from you or others list members, thanks a lot.

If code is modified version of GPL code, or links with it at compile
time, then it is still GPL.  This is true no matter how trivial are the
changes you made.

But, you can write a routing protocol (such as OSPF) that uses BSD or LGPL licensed
XRL logic to talk to the xorp core.  As long as the XRL and other Xorp BSD/LGPL licensed
code is the only Xorp code you use/link-with (and all other code to implement OSPF is your
own property), then you can license it proprietary if you want.  Any changes you
made to the GPL core logic (fea, rib, etc) would still have to be release GPL.

Or, if you re-write the CLI module and only use the XRL glue logic
from XORP and all other code is yours, then you can license your
CLI module proprietary.  You just need to make sure that you are not linking
with any GPL licensed modules.

Please note that I Am Not A Lawyer, and my comments should not be considered to
be guaranteed to be correct.  If you decide to try using proprietary
modules with Xorp you should consult a real lawyer and read the GPL and
LGPL licenses closely yourself.

Thanks,
Ben

-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com