This node only keeps track of the netfilter connections if they live. Dead connections are deleted automatically from the table. This deletion happens based on the set timeout period. The longer the timeout period, the longer the record of the connection will stay in the tracking table. The value of this option is in seconds. By default, the value is set to 4,32,000 seconds or 12 hours. We can check the current value using the following command:
# sysctl -a | grep nf_conntrack_tcp_timeout_established
By reducing this value, we can keep the tracking table lean which is faster for a high-traffic node. It should be noted here that lowering this value might also break long running idle TCP connections.
