neutron-lib/api-ref/source/v2/samples/security-group-default-rules/security-group-default-rule-create-request.json

{
    "default_security_group_rule": {
        "direction": "ingress",
        "port_range_min": "80",
        "ethertype": "IPv4",
        "port_range_max": "80",
        "protocol": "tcp"
    }
}