Morgon J. Kanter wrote: > Hi, > > Apologies if I'm on the incorrect list, but this isn't a patch for netfilter > so I believe this to be the appropriate one. > > I'm in the process of writing an application that requires notification when a > new TCP connection to a specific destination is established, and finished / > timed out. I've never used libnetfilter_conntrack (or anything netfilter at > all, for that matter), so I've been investigating using libnetfilter_conntrack > for this purpose. My question is: is this possible to do with this library? Look at utils/conntrack_events.c, I think that example is more or less what you need. > My question is so basic because I'm not really sure what nfct_catch() actually > fires on. I noticed the filter infrastructure -- to get such an application to > work, would I create a filter for TCP, and that destination, and then do > something like: > > nfct_filter_attach(nfct_fd(conntrack_handle), filter); > nfct_callback_register(conntrack_handle, NFCT_T_NEW, new_connection_callback, > NULL); > nfct_callback_register(conntrack_handle, NFCT_T_DESTROY, > dead_connection_callback, NULL); > nfct_catch(conntrack_handle); The filter infrastructure is there to attach filters in kernel-space. > Is this the right track for what I want to do? My issue is I just don't really > understand exactly what nfct_catch does -- what is a conntrack event, exactly? > And what does it mean to steal one, as per the callback returning > NFCT_CB_STOLEN. nfct_catch() receives conntrack events from kernel-space, by default it blocks waiting for events. NFCT_CB_STOLEN means that the conntrack object is not released after the callback. Good luck with it. -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
