Hello all

we are seeing these kind of logs in a Debian GNU/Linux 11 using kamailio 5.5.6

Sep 21 17:41:13 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155702]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:164.152.22.248:5060)
Sep 21 17:41:13 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155698]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:208.74.138.184:5060)
Sep 21 17:41:13 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155695]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:208.74.138.181:5060)
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155693]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:38.102.250.60:5060)
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155707]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:87.1.1.27:5060)
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155707]: ERROR: tm [ut.h:302]: uri2dst2(): no corresponding socket for "87.1.1.27" af 2
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155707]: ERROR: tm [t_fwd.c:470]: prepare_new_uac(): can't fwd to af 2, proto 1  (no corresponding listening socket)
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155697]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:208.74.138.184:5060)
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155694]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:192.40.216.97:5060)
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155694]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:208.74.138.180:5060)
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155714]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:87.1.1.27:5060)

The kamailio instance we are using is receiving around 1500 calls per second in average when we do start seeing these errors more frequently
In this instance we are using multihomed
the listen address list is

children=14
socket_workers=1
listen=udp:192.168.99.70:5081
listen=udp:192.168.99.81:5060
listen=udp:87.1.1.27:5060
listen=tcp:192.168.96.105:8095
listen=tcp:87.1.1.27:5060
tcp_children=6
port=5060

We use the first worker only to perform the OPTIONS requests from the dispatcher module.
The sockets 
listen=udp:192.168.99.81:5060
listen=udp:87.1.1.27:5060
are used to communicate both A and B legs

so when a message is received at 192.168.99.81:5060 we send it to 87.1.1.27:5060 and viceversa
We were using $fs variable before doing the t_relay() function. 
This way is working, but when load increases, seems sometimes kamailio doesn't get the proper socket to forward the reply.
I think the errors mainly are related to responses which are being forwarded, like if the function get_sock_info_list was not able to retrieve the listen interfaces

we have tried to set in the onreply routes the commands
set_recv_socket("udp:192.168.99.81:5060");
set_send_socket("udp:87.1.1.27:5060"); (when reply goes from private to public domain)

and it seems it reduces the number of 
Sep 21 17:41:13 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155702]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:164.152.22.248:5060)
Sep 21 17:41:13 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155698]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:208.74.138.184:5060)
Sep 21 17:41:13 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155695]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:208.74.138.181:5060)
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155693]: ERROR: <core> [core/forward.c:183]: get_out_socket(): no corresponding socket found for(udp:38.102.250.60:5060)
errors

But i honestly don't know why the 
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155707]: ERROR: tm [ut.h:302]: uri2dst2(): no corresponding socket for "87.1.1.27" af 2
Sep 21 17:41:14 lax-dedge-1 /usr/local/kamailio/sbin/kamailio[3155707]: ERROR: tm [t_fwd.c:470]: prepare_new_uac(): can't fwd to af 2, proto 1  (no corresponding listening socket)
appear

We aldso tried to increase the kernel buffers rmem and wmem from 208KB (as we had by default) to 4MB

Do you know a reason which could cause these logs to appear?
Any setup that could mitigate them?

thanks a lot and regards
david escartin
--
David Escartín
NOC engineer
www.sonoc.io
LinkedIn
Twitter
Instagram
This e-mail is for the exclusive use of its recipients and may contain business secrets or other confidential or privileged information. Any unauthorised use, copying, publication or distribution of this e-mail is strictly prohibited. If you are not the intended recipient, please inform us immediately by replying to this e-mail and delete it, including any attachments or copies on your system.

In accordance with the GDPR (EU) 2016/679 and the LOPDGDD 3/2018, we inform you that this e-mail address and/or any other personal data you have provided us with will be treated by SONOC with absolute confidentiality and with the only purpose of providing you with the requested services, due to your condition as a client, supplier or because you have requested information from us at any time. These data will only be kept for as long as required to comply with legal obligations. You can exercise your rights at any time by sending an e-mail to: dataprotection@sonoc.io.