The router container requires "ulogd" package in addition to "iptables" (For ulogd configuration, see https://hangarau.space/running-and-debugging-iptables-inside-a-docker-container/)
IPT -I FORWARD -s 0/0 -d 0/0 -j NFLOG --nflog-prefix "[default]:" --nflog-group 1
# Log all forwarded packets
The logs will apear at /var/log/ulogd_syslogemu.log
Add a route to the network through the eth0 network interface using as a gateway
ip route add <subnet> via <ip addr> dev eth0
Run it on "host" containers