Hi Anand, On 16 April 2015 at 16:45, Anand Buddhdev <anandb(a)ripe.net> wrote: it's safe, but then it will do exactly that and it will start listening on nothing. There is no automagic default. it may and it may not, this applies for both recvmmsg/recvmsg backends. The thing is that while ANY works well for TCP, since each connection gets a new socket with correctly set endpoints, it is not like that for UDP and the application has no* control over the source address. _Usually_ the operating system selects the right address (right meaning "most appropriate"), but it shouldn't be relied upon. Your best bet is to template it, since there are no variables in the configuration, or stick with the ANY but don't rely on the outgoing address for things like ACLs and such. Maybe someone else has a better idea? Marek * At least not portable.