See AGPLv3 13 (Remote Network Interaction).Notwithstanding any other provision of this License, if you modify the  Program, your modified version must prominently offer all users  interacting with it remotely through a computer network (if your  version supports such interaction) an opportunity to receive the  Corresponding Source of your version ...Assume I'd want to write a VNC server. It is clear that the user does not directly interact with the software but rather with the applications displaying on the framebuffer which is serverved by the software.  However, it is still technically possible for the software to inject some text/information (e.g. for some seconds on the first connect) into the framebuffer being encoded that prominently offers all users interacting ... the corresponding source.  As far as I understand this requirement for the source code offer only applies if the program was modified - right?  So would I have to ship this functionality (injecting a prominent message in the framebuffer) in the source so that someone who modifies the code has an easy way to activate this framebuffer overlay in order to comply with the license?If not, how could someone modifying the source comply with the license?Since this overlay might be quite annoying It should not be required for users who e.g. install a debian package.But Linux distributions normally do make modifications to source codes, hence thez would have to enable this nag screen - right ?If so, do modifications like security patches or other distribution specific patches (like path changes etc.) count as modifications ?If that is the case, how would one make an exception that distribution specific patches must not trigger the prominent offer requirement ?
AGPLv3 13 and non-interactive software
agpl 3.0
You'll find a similar issue in the GPL FAQ:For software that runs a proxy server licensed under the AGPL, how can I provide an offer of source to users interacting with that  code? For software on a proxy server, you can provide an offer of  source through a normal method of delivering messages to users of that  kind of proxy. For example, a Web proxy could use a landing page. When  users initially start using the proxy, you can direct them to a page  with the offer of source along with any other information you choose  to provide ...Although a proxy server is quite different from a VNC server it is a perfect example to understand the license authors' intention: Use any available means to display the offer of source.So as you've correctly pointed out it is possible for a VNC server to display (actually draw) a message and therefore someone who modifies the code is obliged to use this functionality for the offer of source.My advice is that you implement this feature in your official version and add an option (via config file) to disable this feature. Something like this:# This program is distributed under the terms of the AGPLv3.# If you have modified the program, your modified version must prominently offer# all users interacting with it an opportunity to receive the corresponding# source of your version.# See http://www.gnu.org/licenses/agpl-3.0.en.html#section13 for details# # YOU MUST NOT DISABLE THE FOLLOWING OPTION UNLESS YOU HAVE NOT MODIFIED THE# SOURCE CODE#SHOW_SOURCE_OFFER=TRUESOURCE_CODE_LINK=http://link.to.your/sourcecode.tar.gz 