<div>Stefan, Can't you achieve the same thing by reserving an early block of priorities (and a late one, for system stuff that should be done late)? If you use negative numbers, then you lose the capability of ever extending priorities to interpret the negative number as "from the end" as done in ebtables/iptables line numbers. I think that is more useful, and having to do that outside of priorities would mean extra parsing and encoding to get that effect. I also think that nwfilters ought to reflect the underlying filter mechanisms as much as possible. Really, I'd prefer they were simply parameterized shell scripts of ebtables/iptables commands run at significant events (start-up, shutdown, migrate) instead of XML-encoded things. Then the full feature sets of ebtables/iptables would be available "for free", instead of requiring libvirt patches to, e.g., add "return/continue" or multiple chains. Barring that, at least I think what nwfilters provides should be a close map to ebtables/iptables capabilities. Mapping line numbers into a wide range of priorities is straightforward, but if you use negative numbers in an ordinary sort, you can no longer use the sign as ebtables/iptables does. Because you've limited the range, you could do something hacky with offsets (anything below "-1000" is "from the end" or some such), but that's arcane. Using priorities in multiple places is very like programming in basic and what both ebtables/iptables and nwfilters could use better I think would be the capability to label rules by name and reference the label to identify the rule location. Then you might, e.g., add a rule at "myrules + 5" and don't care what particular priority/line number "myrules" is. +-DLS </div>