Restrict access to my SystemImager server

[cornelius]

I'm now using SystemImager for backing up and installing my systems in my local network. I followed this howto http://www.howtoforge.com/howto_linux_systemimager, and all is working like expected. Now I have a little question: I'd like to restrict the access to my image server, i.e., I have certain IP adresses that should be allowed to retrieve images from the image server, but all other IP addresses should not be allowed to access the image server. Is this possible, and if so, how?

Cornelius