Thanks for the speedy response as always.

The current scenarios are taken from Asterisk only, Kamailio is not yet in front of it - so no record route headers.

I imagine the ACKs aren't being sent due to it being a waste of resources as you suggest, but I'm interested in detecting these in Kamailio so I can add them to a block list if they exceed a certain limit.

On Tue, Apr 5, 2016 at 12:12 AM, Alex Balashov <abalashov@evaristesys.com> wrote:

I am assuming you're adding Record-Route to your initial INVITEs?

If so, in the case of the answered call, it might be a defective UA that doesn't follow Record-Route for in-dialog messages (which include e2e ACK).

In the case of the negative replies, a scanner might not waste additional resources sending a formally requisite ACK. It'll just move on to the next target, and leave you holding the bag on the unacknowledged failed transaction.

-- Alex

--
Alex Balashov | Principal | Evariste Systems LLC
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