Good evening,

During pre-production testing, we discovered quite odd IPv6 socket issues. Problems arise when a SIP dialog is initiated from within Kamailio (e.g. a SIP INVITE message).

Using ngrep, it seems very odd IPv6 sockets are opened, for example:

U 2001:beef:34a:10::234:5060 -> 2001:beef:285:1::3:5060 1573541542@0:1440
U 2001:beef:34a:10::234 -> 2001:beef:285:1::3 +1573541542@1448:17

Obviously the "1573541542@0:1440" part is bogus, I expect output similar to:

U 2001:beef:34a:10::234:5060 -> 2001:beef:285:1::3:5060
INVITE sip:s@[2001:beef:285:1::3]:5060 SIP/2.0.

When I do a REGISTER from UA using IPv6, the dialog (and return packets) seem completely normal.

Using IPv4, there's no problem at all.

It seems the socket problems are triggered when:
  1. Using the topoh module.
  2. When altering From: headers e.g. using uac_replace_from().

When topoh is disabled and no headers are altered, IPv6 works as good as IPv4.

We could reproduce the problem using Kamailio 4.1.4, 4.1.5 and 4.2.0 on Debian (64-bit).

Please advice what to do.

Thanks in advance!

Best regards,
Kees