Ok, so newer kernels opted for performance, giving that on 99% of the time only nf_conntrack_netlink uses event notifier callbacks, which is usually the case... But I am curious...what if another kernel module needs to receive conntrack events? Are there any way to keep track of events in kernel space while nf_conntrack_netlink is holding the one and only callback hook? Thanks Pablo! Luca On Thu, Nov 12, 2009 at 1:13 PM, Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote: > Luca Pesce wrote: >> >> Hi Pablo, >> I was looking at conntrack events callbacks and conntrack tools too. >> As you said in your mail, only one callback can be registered, so if >> nf_conntrack_netlink module is loaded, no other modules can register a >> callback for events. >> >> If I correctly undertand the code, it seems that in the past kernels >> this limitation was not there. > > Indeed. This limitation was introduced recently > >> For example, 2.6.21.5 version had a >> notifier chain declared in nf_conntrack_ecache.c: >> >> ATOMIC_NOTIFIER_HEAD(nf_conntrack_chain); >> >> and nf_conntrack_register_notifier() simply adds an entry (callback >> block) to the chain, so many callbacks could be registered for >> conntrack events. Am I right? > > Yes. > >> Why has this been changed nowadays? > > Because the notifier chain added too much overhead for the only single > client (nf_conntrack_netlink) in the kernel code. > -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
