I just discovered (via a Google search) that the City of Masks ebook has been uploaded to Scribd, under an Attribution-Noncommercial Creative Commons license.
Now, in fact I have never released the ebook under any CC license. I have released the audio version (the podcast) as CC-Attribution-Noncommercial, but not the ebook. So I'm within my rights to complain to Scribd that this violates my copyright, and have it taken down.
I'm not going to do that, not right now, anyway, because I don't see that it's doing me any great harm (and it may do some good - someone may read it, like it, and seek out my other work here). I suppose for legal reasons I should say that I'm not giving up my legal rights by deciding not to exercise them at this time and on this occasion, blah blah.
City of Masks is in my copyright. I choose to distribute the ebook, from my own website, and not charge any money; I can do that because I own the copyright. I would prefer the file not to be uploaded elsewhere, because if it is on my own site I can control it. (Recently, for example, I put in a note at the end directing people here. I can't do that to the copy on Scribd.)
Technical ways to effectively prevent anyone at all with an internet connection taking the file and doing anything at all to it do not exist and never will, and I won't make life more annoying for honest people by implementing the ineffective ones that do exist. As I remarked above, at the moment I am also choosing not to pursue my legal ways to prevent this; it's just not worth it to me and I don't want to be the Copyright Ogre.
However, if you're thinking of uploading the file somewhere yourself, I have two words for you: Please don't.
Link to the copy on my site instead. Thanks.