meta-google/recipes-google/networking/gbmc-bridge/50-gbmc-br-cn-redirect.rules

table bridge filter {
    chain gbmcbr_mark {
        type filter hook prerouting priority -300;
        iifname == "cn0" mark set 1 return
        iifname == "cn1" mark set 2 return
    }
}

table inet raw {
    chain gbmcbr_nat_input {
        type filter hook prerouting priority -300;
        # client should only use 10166 for this purpose and
        # it should NOT use service port directly
        # otherwise drop later if the packets goes into input
        tcp dport 10167-10168 mark set 0xff
        mark 1 tcp dport 10166 tcp dport set 10167 notrack
        mark 2 tcp dport 10166 tcp dport set 10168 notrack
    }
    chain gbmcbr_nat_output {
        type filter hook output priority -300;
        tcp sport 10167 tcp sport set 10166 notrack
        tcp sport 10168 tcp sport set 10166 notrack
    }
}