Please find in the attachment another patch. It implements MAC-Address based access control.
I use "git" at home. This patch is created against my "portable" version of minidlna, see 2928850 and 2928851 in the patches tracker. I was unable to use "cvs diff" since my other patches are not applied upstream yet. I hope you will be able to apply this patch nevertheless. If not, please let me know.
To use this feature, add in the config file something like