<div dir="ltr">Hi Danny,<div><br></div><div>It is difficult to do a full analysis of your issue without a PCAP trace and kamailio proxy logs in verbose mode of both the REGISTER message and the following natping.</div><div><br></div><div>When NGCP receives a REGISTER message it should store in the location the the "path" parameter that contains: the LB internal sip interface and the LB external sip interface (socket). These information should be used by the natping process to sent the OPTION messages to the devices.</div><div><br></div><div>Please check the information stored in the location to see if everything is stored correctly. You can use the command:</div><div><span style="background-color:transparent"> <b>ngcp-usr-location </b></span><b><span style="background-color:transparent">--subscriber username@domain </span><span style="background-color:transparent">--verbose</span></b></div><div><br></div><div><span style="background-color:transparent"><br>Thank you</span></div><div><span style="background-color:transparent">Marco</span></div><div><br></div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Sat, Jun 27, 2026 at 12:12\u202fPM Danny Cappellari | ConnectLife S.p.A <<a href="mailto:cappellari@connectlife.it">cappellari@connectlife.it</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg4892028181434530030">
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<div>I would like to report several critical errors in /var/log/ngcp/kamailio-proxy.log<br>
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ERROR: <core> [core/udp_server.c:821]: udp_send(): sendto(... dst:(<a href="http://1.2.3.5:5060" target="_blank">1.2.3.5:5060</a>) ...) - err: Invalid argument (22)<br>
CRITICAL: <core> [core/udp_server.c:828]: udp_send(): invalid sendto parameters ... server is bound to localhost and attempts to send to the net<br>
ERROR: nathelper [nathelper.c:2458]: nh_timer(): sip udp_send failed<br>
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<b>Cause</b><br>
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This is the nathelper / NAT keepalive (natping) proxy module. From the active config:<br>
- natping_processes = 7, natping_interval = 30<br>
- no natping_socket defined.<br>
<br>
<b>The proxy sockets are <a href="http://127.0.0.1:5060" target="_blank">127.0.0.1:5060</a>, <a href="http://1.2.3.4:5060" target="_blank">1.2.3.4:5060</a>, <a href="http://127.0.0.1:5062" target="_blank">127.0.0.1:5062</a>.</b><br>
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REGISTERS arrive at the proxy from the load balancer via loopback, so the socket stored for contacts is 127.0.0.1. When natping tries to send a keepalive to the contact's public IP using the loopback socket as the source, the kernel rejects sendto() with EINVAL(22)
\u2192 "server is bound to localhost". With ping_nated_only=0, it also tries non-NAT peers.<br>
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<b>Impact</b><br>
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- CPU waste on the 7 natping processes and hundreds of MB of logs per day (risk of filling up the /var disk).<br>
- NAT keepalives don't work for anyone: the NAT pinholes of phones actually behind the NAT are no longer refreshed \u2192 after the NAT timeout, incoming calls to those phones may no longer arrive.<br>
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Do you have any solutions?<br>
Version mr-13.5.1</div>
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