[VoiceOps] Ghost calls - Sipvicious?

Jimmy Hess mysidia at gmail.com
Tue Nov 12 21:40:00 EST 2013

On Tue, Nov 12, 2013 at 6:05 PM, Hiers, David <David.Hiers at adp.com> wrote:

> Maybe someone is spoofing your SBC IP address?

> I can't see what useful info would be gained from such spoofing, but
> enough of these could DOS you pretty hard.

I would suggest capturing packets towards the devices experiencing it,
behind the NAT device, using Wireshark -----   I would wonder first if
either the  NAT/ACL  isn't working as designed;  or traffic is coming from
a SIP ALG /  inside the NAT;  spoofing the SBC's  source IP seems terribly

I think it's more likely, there's an unexpected way the Polycom is being
contacted,  such as a proxy service on a router.

Then there is that matter of;    "Does your NAT device verify the foreign
IP address of reverse traffic  like a full stateful firewall would,   or
does it just  check  the destination port number on an incoming packet,
 and immediately   translate  to internal IP based on the destination port
number  and forward  to the internal device?"

In the latter case,  the internal device might be contacted on port 5060
 from other  internet hosts  scanning the ephemeral port range;   if that
5060 from the internal device  has recently been used as a source port from
the Polycom contacting the SBC.

So a full packet capture from the network with the handsets, could give you
a better idea,  of what you are seeing.

> David
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://puck.nether.net/pipermail/voiceops/attachments/20131112/c1bd8819/attachment.html>

More information about the VoiceOps mailing list