The conntrack-tools are a set of tools targeted at system
administrators. They are conntrack, the userspace command line
interface, and conntrackd, the userspace daemon. The tool conntrack
provides a full featured interface that is intended to replace the old
/proc/net/ip_conntrack interface. Using conntrack, you can view and
manage the in-kernel connection tracking state table from userspace. On
the other hand, conntrackd covers the specific aspects of stateful
firewalls to enable highly available scenarios, and can be used as
statistics collector as well.

https://conntrack-tools.netfilter.org/
https://www.netfilter.org/projects/conntrack-tools/