Knockd question - Help I'm stumped.

I've been doing alot of reading about knockd since I'm setting up a home server and want it to be secure. I only want to open ports on demand. The question I have is, is it possible to only accept knocks from a specific IP address or range of IP address's.

I have a shell account, that I will set my knock script up on. When I want to connect I will run that knock script from the shell account w/static ip. I want knockd to ignore any knock requests that come from any other ip.

Thanks