On Fri, 4 Apr 2025 at 14:05, Pyry Aaltonen via sr-users sr-users@lists.kamailio.org wrote:
I understand, yes, that it comes from the os default settings how the tcp connection is handled, but as far as I understood that the patch done in the commit is adding the TCP_USER_TIMEOUT which should somehow at least try to fix this behaviour?
I think you are misinterpreting what TCP User Timeout does.
It detects a broken TCP connection when *actively* writing to this socket. It cannot detect a broken connection in absence of any data written to the socket.
I think you are probably looking for TCP keepalives instead and Kamailio provides tcp_keepalive / tcp_keepcnt / tcp_keepidle / tcp_keepintvl options for this purpose.
In both cases (TCP User timeout vs TCP keepalives) Kamalio sets socket options advising the kernel about the configuration. I suggest you read the kernel documentation to understand more about those OS features.
If you are doubting that Kamailio sets the correct socket options I'd suggest using strace to verify.
Lukas