Ok thanks that seems to have worked. Its showing me that theres a constant stream of UDP requests from an ip address to the sip port (5060).
If i stop my sip proxy then the outbound traffic goes away, but the inbound traffic doesnt stop.
Also despite me putting reject or block rules against that IP address, when i restart the sip proxy, the outbound traffic starts back up again, suggesting that the firewall isnt blocking the traffic for some reason.
A packet capture shows that the incoming traffic is a SIP packet "REGISTER sip: SIP/2.0" and the outbound replies when the proxy is enabled are "Status-Line: SIP/2.0 407 Proxy Authentication Required"
Does this indicate a brute force attack of some kind ? or am i missing something obvious here?
The IP in question doesnt appear to be related to my SIP provider, so i dont think its them, but thats my next port of call.