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I wanted to know if Cox can see the Mac addresses in my network. I know they can see IP addresses, but are Mac addresses included? What if I use a VPN?
Cox can "see" the MAC address of your modem because Cox needs this MAC address to assign a public IP address. As far as devices on your private network, no...Cox can't see those private IP or MAC addresses.
I don't think Cox can see the private IP of your router. I once read an ISP can only see something (i.e. router) is connected to the WAN port of the modem. Therefore, I think Cox can only see something is connected and possibly its capability (Fast Ethernet, GigaE, etc).
If you subscribe to a VPN, yes, Cox can see your public IP address but cannot see where you're going or what you're sending. All they see is their assigned-public IP address with bunch of gobbledygook trailing behind it.
Bruce said:Cox can "see" the MAC address of your modem
I think you mean router. Cox needs the WAN MAC address in order for DHCP to work. Together with the IP assigned is known as the Customer Premise Equipment or CPE. Since the IP changes, Cox keeps the CPE on file for many months.
Don't modems have MAC addresses? I thought an ISP would just communicate with the public-side of the modem and couldn't care less what's connected to its private WAN port...unless they "drilled down" to help troubleshoot..
What if I connect a Roku to the WAN port? Would my Roku be public? What if I connect nothing to the WAN port? Would the modem not get an IP address?
The modem has a MAC address and Cox keeps track of it but not for DHCP. Also, it's not what is plugged into the WAN port they track, but the WAN MAC of the router itself. You plug the modem into the WAN port.
Bruce said:What if I connect a Roku to the WAN port? Would my Roku be public?
The Roku would be offline. If you plug it direct into the modem then yes, it would be public and Cox would track the MAC address. Notice I say "modem" and not router or gateway(modem/router combo), for then it would not apply unless Cox has some network monitoring service running.
This is how I thunk it worked: the modem is both a DHCP client and a DHCP server.
If the modem boots...as a DHCP client...it sends a DHCP Request to the Provider, The Provider responds and assigns a public IP to the modem.
If the router boots and connects to the modem, the router sends a DHCP Request to the modem and the modem...as a DHCP server...assigns a sub-netted address to the router. This sub-netted address shouldn't be "seeable" and tracked due to IP exhaustion.
In regards to DHCP clients and servers, there is also a DHCP helper...which would be the modem....but would just forward the public IP to the router. Is this what Cox is doing: DHCP helping? My router isn't doing this.
Bruce said:the modem is both a DHCP client and a DHCP server.
The modem acts as a transparent bridge between the router and Cox's DHCP servers. It also acts as a client on a private 10.x.x.x subnet that is used for troubleshooting only. There is no server on the modem itself.
Not a "server" per se as a network service but running a dedicated service to what's connected to its WAN port.
Does Cox approve or update the firmware of my router?
Bruce said:Does Cox approve or update the firmware of my router?
Nope, the firmware is stored locally on the router's flash. The router manufacture updates the router support page with the latest firmware. Some router's have automated systems that check the firmware automatically. You may be confusing router firmware with modem firmware, which Cox does control.
Bruce said:it sends a DHCP Request to the Provider, The Provider responds and assigns a public IP to the modem.
How this works is somewhat complex. See link below for a layout of the process.
I understand modems and routers each have chipset and firmware but if Cox is to communicate directly with my router and my router allows me to set some huge MTU, will Cox comply with my choice?
I don't think Cox communicates directly with my router. Maybe they do...I obviously don't know. However, I wouldn't want them to. Just as I wouldn't want them communicating with a directly-connected laptop. I always thought the demarc was the modem but now it's extended to the router.