I've been tasked to use LD_PRELOAD to log SSL keys for TLS connections using a Diffie-Hellman cipher. The first attempt did not work, so I wanted to sanity check whether Kamailio's TLS support is built in such a way that would defeat LD_PRELOAD.

The instructions from the vendor are to update /etc/init.d/kamailio like this:

env SSLKEYLOG_UDP='127.0.0.1:1234' LD_PRELOAD="/usr/local/src/voipmonitor-git/tools/ssl_keylogger/sslkeylog.so /usr/lib/x86_64-linux-gnu/libssl.so.3" \
start-stop-daemon --start --quiet --pidfile $PIDFILE \
--exec $DAEMON -- $OPTIONS || log_failure_msg " already running"

Is there anything special in Kamailio (5.7.3 on Debian 12) that would prevent this from working? Not necessarily something to defeat a keylogger, but maybe the way tls.so gets loaded?

The only discrepancy I've noticed is the vendor docs refer to libssl.so.3 not libssl.so.1, but the vendor said that should be OK.

I'd love to hear from someone already using VoIPmonitor with Diffie-Hellman ciphers and Kamailio.