During testing of a custom packet filter, I ran into a situation where it seems like the filter was unloaded.  When 
listing the filters in the chain, it wasn't present, and remounting the packet filter seemed to return things to normal.
 I haven't been able to reproduce the issue, but I'm still a bit worried about not understanding the specific cause. I 
know I can cause the filters to be unloaded by using umount on the /dev/io-net/X device, but calling ifconfig up or down
 does not seem to have an effect. From the Core Networking documentation, I see "detach" seems to be the key word, but I
 can't seem to find a definition of what this is.  What are the events that can cause this to happen?