site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com On Mar 9, 2007, at 12:32 AM, Jones Curtis wrote: = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... I'm trying to determine the ethernet interface (en0, en1, etc.) that will be used for a given destination ip address. I've tried using ifaddr_withdstaddr() and ifaddr_withnet() and I can get the correct result for addresses that are local to the machine and for those that are on the same subnet as one of the ethernet interfaces for the machine. So, that's part of the solution, but not all of it. I looked at ifaddr_findbestforaddr(), thinking that it might return NULL if that the given interface wasn't useful for that address, but if I'm reading the source code for ifaof_ifpforaddr() correctly, it doesn't touch the routing tables and it simply returns the first address entry if none of them match. So, I'm guessing I need to specifically find the interface for the default route if _withdstaddr() / _withnet() don't help. Is this the correct approach? And how would I go about doing that? It's my understanding that advisory forms of the kernel's routing policy decisions are not exported to userspace. There are good reasons for this; not the least of which being that between obtaining such advice and actually committing to a decision based on that advice, the validity of the advice may expire due to changes in the system's topology. I realise this doesn't help you much, but telling the future is a tough business. 8( This email sent to site_archiver@lists.apple.com