There are cases where you want to monitor a specific type of connection going from/to/through your router. The following example run via SSH tracks DNS requests towards name servers.
watch -tn5 “conntrack -L -p udp –dport 53 | sort -nrk3; echo; conntrack -L -p tcp –dport 53 | sort -nrk3”
The number 53 refers to the port used for DNS. In the above case, this includes both udp and tcp. You can change this to any relevant port (for example, only 443) to change the command scope.
watch -tn5 “conntrack -L -p tcp –dport 443 | sort -nrk3”