Hi, I have a kamailio 4.4.5 (x86_64/linux), running as a proxy in front of asterisk, handling udp/tcp/tls registration, using udp towards asterisk. Over time memory is consumed and the Passive Open TCP sessions is increasing until we run out of memory and a restart is needed. Sep 11 06:25:03  ERROR: <core> [mem/f_malloc.c:415]: fm_search_defrag(): fm_search_defrag(0x7f9d55184000, 34120); Free fragment not found! Sep 11 06:25:03  ERROR: <core> [mem/f_malloc.c:498]: fm_malloc(): fm_malloc(0x7f9d55184000, 34120) called from tls: tls_init.c: ser_malloc(275), module: tls; Free fragment not found! This image contains graphs that show the behaviour: https://imgur.com/68PvmyA Should it behave like this? Is there a knob to twist to change behaviour? tcp / tls stuff from kamailio.cfg: enable_tls=yes tcp_max_connections=8196 tls_max_connections=8196 tcp_no_connect=yes # Don't try to connect - drop if there is no session tcp_connection_lifetime=3605 modparam("tcpops", "closed_event", 1) modparam("usrloc", "handle_lost_tcp", 1) modparam("usrloc", "close_expired_tcp", 1) in the registrar route I have: tcp_keepalive_enable("60", "5", "5"); /niklas