Keeping wifi active during lock So I can find no good solution to this. I have a macbook pro running yosemite that will take down the interface when I lock it. How can I configure it so the network connection stays active when the computer is locked?

Also note that recommendations to install "lock me now" as a workaround won't work, as that app isn't available in my area (according to the app store).
I'm assuming when you say "Lock" you mean that the screensaver kicks in so that you are prompted for a password.

I use an app called Amphetamine (https://itunes.apple.com/us/app/amphetamine/id937984704?l=en&amp;mt=12). It will make sure your Mac stays awake, but still allow it to start the screensaver (ie locking it). This way, any network activity continues (downloads, streaming, etc.), but your Mac is password protected.