[SR-Users] Configuring TCP keep alive and connection lifetime

"kamailio" <users(a)lists.kamailio.org>rg>, Hi I am sorry to ask again about this topic but I don't understand yet how the TCP keep-alive are sent. With Kamailio 3.0.1 and the following configuration: tcp_keepalive=yes tcp_keepidle=10 tcp_connection_lifetime=3600 The TCP connection is kept alive and TCP Keep-Alive packets are sent when the TCP connection is idle. But I don't understand why the time between KA is not linear: first KA is sent 10 seconds after last last TCP message. This is logical and connected with the tcp_keepidle=10 configuration. then 2nd KA is sent 75 seconds after first KA Then my client sends some traffic and 23 seconds after last message, a new KA is sent. Another time it was 54 seconds. etc. etc. Could you explain me where do come from these values of 75 seconds, 23, 54 ? Everything works well: my client behind NAT is kept connected but I'd like to understand why it does work :-) Thanks in advance, Pascal