The customer's router is for the customer to configure
I think ideally the customers router shouldn’t be touched, but the ISP can still do packet filtering on the next hop to drop any packets which don’t have a src ip matching the assigned WAN address of the router.
Indeed, though we're at the mercy of the tyranny of the default.
I think ideally the customers router shouldn’t be touched, but the ISP can still do packet filtering on the next hop to drop any packets which don’t have a src ip matching the assigned WAN address of the router.