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Question on 'Use Computer MAC address'
I just signed up fo xfinity service (cable company here in the US).
the connection (cable modem=>ethernet cable=> pc) works just great.
However, when I put netgear router in between cable modem and a pc, I was getting no internet up until I switched to 'Use Computer MAC address'. The netgear router works like a charm and this is not a hardware router issue or anything like. This is more how xfinity delivers services...
Could someone explain to me why I must have my PC's mac cloned by the router?
I read couple other posts on this claiming that this is because ISP only allows one MAC per cable line. But this makes no sense, because when I use a different laptop with different MAC all works just fine.
The "Use computer MAC" is for those silly ISP which take and keep the previously connected computer MAC address on the cable modem so the Cable Modem does not have to be rebooted after used/tested with that very same computer [direct connected], and you don't have to call the cable TV operator.
If you don't have a problem, do not enable this feature: Because it will kill your Internet connections because the (again very same silly ISPs) allow just one MAC address - and when changing the MAC address of your router (this is what happens, the computer MAC will be copied to the router WAN/Internet port!) your router will not be able to get a public IP address.
For some ISP, rebooting the cable modem (and wait five minutes till it's provisioned again) and then bring up the router will most likely fix things - and no need for stories or wasting the ISPs support resources.
7 Replies
> [...] But this makes no sense, because when I use a different laptop
> with different MAC all works just fine.They could keep a list of valid MAC addresses, and still not know
about your new router. I know nothing, but it's possible that they'll
accept the first two addresses they see, or all that they see in the
first few minutes after the initial connection, or ...
The threat is that if a cable-TV type ISP didn't track your MAC
address(es), then some evil-doer could tap into cable, and steal the
service.If you set the router's (WAN) MAC address back to its default, and
reconnected it to your (unspecified) "cable modem", and then called
Comcast, and gave them the appropriate MAC address, then I'd guess that
all could be made well. (At least in this one dimension.)No, I am not sure that what you said is a complete picture of an issue. for the same cable modem, for the same ethernet cable I can literally have dozens of dirrent computers that I can plug in interchangeably to that one cable and every time the connection will deliver internet.
I think there are other reasons why MAC address a pc needs to be spoofed by a router...
My hunch it has has to do with the headers on how PC/router send and receive information.
> [...] I can literally have dozens of dirrent computers that I can plug
> in interchangeably [...]Did you "literally" try "dozens of dirrent computers", or are you
getting your "facts" from the White House press office?> My hunch [...]
If I really wanted to know, and I were a Comcast customer, then I'd
try asking Comcast before I started inventing fanciful stories. But
that's just my own attitude.