[SR-Users] Detecting calls with missing ACK (Lazy SIP scanners)

[Marrold]

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 at 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
> 1447 Peachtree Street NE, Suite 700
> Atlanta, GA 30309
> United States
>
> Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
> Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
>
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