Hello,

to add to this topic: tls module runs smooth when no other module uses an external library that is linked also with tls, I didn't have issue with in the past few years.

But if another module that indirectly links also the libssl, I also got random crashes, usually during events when kamailio code is not involved at all. For example, a while ago using the http_client module (which uses libcurl that linked also libssl) resulted in sporadic crashes during tls handshake -- that's all in libssl, nothing to do with sip traffic at that stage. And actually there were also crashes when opening the connection to the https server. The behaviour was non-deterministic, months without any issue, then 1-2 crashes in a week or so, then all good as well. I somehow related it to minor updates of the operating system.

After all, I ended up writing ruxc module to have an alternative http_client() function and from that moment no libssl related crash on the respective system. Strange that on another customer having same OS and using http_client() function, all was and still is fine. So it could be also related to tls settings in both sides of the connection (e.g., ciphers, renegotiation, tls version, ...).

If you migrate to kamailio 5.6.x, then you can also try using tlsa module instead of tls, that should isolate the global libssl contexts, one inside the tlsa and one in those modules linking dynamically libssl.

Cheers,
Daniel

On 23.06.22 16:46, Karsten Horsmann wrote:
Hi Igor, 

I jumped from 5.3 to 5.5.x so I read carefull the changelog and migrate steps. 

https://www.kamailio.org/wiki/features/new-in-5.5.x

Show a bit about tls. 

Igor Olhovskiy <igorolhovskiy@gmail.com> schrieb am Mi., 22. Juni 2022, 21:08:

Karsten,

Thanks for your answer!

Out of your head, were there any significant changes in TCP/TLS on 5.4 -> 5.5 change?

Regards,
Igor
Le 22.06.2022 à 18:11, Karsten Horsmann a écrit :
Hi Igor, 

I also use CentOS 7 with the same openssl version and between 1000 up to 2000 tls/wss connections. 

Works for me. Main difference I use Kamailio 5.5.x

Kind regards 
Karsten Horsmann 

Igor Olhovskiy <igorolhovskiy@gmail.com> schrieb am Mi., 22. Juni 2022, 10:36:
Hello!

Due to I still experience irregular Kamailio 5.4 crashes (like 1/month) related to SSL (using websockets and SIPS) I'm wondering, could openSSL upgrade change the situation?
As of now in CentOS 7 I have 1.0.2k version.

Does anyone have experience to fix crash-related to TLS problems with openSSL upgrade?

Or maye some tuneup of TCP parameters can help here?My current setup is quite simple:

children=4
enable_tls=yes
tcp_accept_no_cl=yes
tcp_connection_lifetime=600
tcp_max_connections=998976 # 1000000 - 1024, so we're leaving 1k for system reserve
tls_max_connections=998976

Number of clients ~ 200 constantly connected to websocket.
--
Best regards,
Igor
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