iptables examples

README.md

 ```
 Note: the `make install` will automatically create, enable and start the systemd service and the `make uninstall` will stop and remove the systemd service.
 
+# Netfiler (iptables)
+
+iptables and ip6tables must be configured to send the DHCPv4 and/or DHCPv6 packets to DHCP Protect for forwarding decision.
+Both DHCPv4 and DHCPv6 can be processed by the same instance of DHCP Protect. However, they must use the same `--queue-num` as in the `dhcp_protect.conf` configuration file.
+
+The `--queue-bypass` will tell iptables to continue to forward packets if DHCP Protect is not running or crashed. It is strongly recommended to keep this option.
+
+## Example IPv4
+`iptables -A INPUT -p udp -m udp --dport 67 -j NFQUEUE --queue-num 67 --queue-bypass`
+
+## Example IPv6
+`iptables -A INPUT -p udp -m udp --dport 547 -j NFQUEUE --queue-num 67 --queue-bypass`
+
 # Configuration
 The configuration file may be tuned, but the defaults should be fine.
 ```