Description of problem:
If the "tun" module is not loaded into the kernel, this can lead to weird issues, e.g. http://bugs.gentoo.org/show_bug.cgi?id=322107
Therefore libvirt should first run a sanity check for "tun" capability/module, before it tries to actually use it.
Version-Release number of selected component (if applicable):
*** This bug has been marked as a duplicate of bug 576702 ***