Monitoring network usage excluding local traffic

Question

I am working on an app that monitors network usage. However I noticed many ways to do this does not allow exclusion of local traffic (say, Time Machine).

I am lookin

Answer 1

I think, an approximate solution: getifaddrs can be used to get statistics on network usage.

It can get separate statistics for Wi-Fi and WWAN interfaces.

You might find more information from :

http://www.gsp.com/cgi-bin/man.cgi?section=3&topic=getifaddrs