I am trying to download the kernel headers for my BBB that is offline, so I cannot use the apt-get utility. After some searching, I found a post pointing me to
http://rcn-ee.net/deb/jessie-armhf/ where I found a package that matches my system. After transferring the package to my BBB I did a dpkg-deb -c on the file to see what was in it. I did not see any header files (.h) mainly kernel modules (.ko). Not sure now I have the right package. Is there a right way to do this when your BBB is offline?