[Matt]

That used to be possible by using " *.*.*.* " and i think it's still possible, you'll just get:

"The ip range *.*.*.* is insecure!
Please set a more precise ip range!"

I'm not sure if they said it was mandatory to have an IP and/or pc id, for security reasons. What i suggest, is just add the client rc to yourself and set your IP through that when needed. I don't think it an IP or pcid is required to use Client-RC, just need to be in server options.