Side effects of cloning Mac adress to router?

What if you clone your Mac adress to the router and later move
your Nics or computers around, couldn´t that mess up the whole
network?

Could it not lead to two points on the network having the same
adress?

Just asking.


Lars
Stockholm

clone it again
or back to default

clone buttons don't disappear

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> What if you clone your Mac adress to the router and later move
> your Nics or computers around, couldn´t that mess up the whole
> network?
>
> Could it not lead to two points on the network having the same
> adress?
>
> Just asking.
>
>
> Lars
> Stockholm

(E-Mail Removed) wrote in news:(E-Mail Removed):

> What if you clone your Mac adress to the router and later move
> your Nics or computers around, couldn´t that mess up the whole
> network?

NO, doing that only affects the WAN port on the router and what the ISP
views as a valid MAC that's been provisioned and linked to your account
that can access their ISP network.

>
> Could it not lead to two points on the network having the same
> adress?

NO, because each NIC MAC is unique and the MAC really only comes into
play when the router is issuing DHCP IP(s) as it links the MAC to an IP
it has issued, which is being kept and tracked by the router in the DHCP
table. You tell the computer to use one of the router's static IP(s) and
the MAC doesn't come into play -- period the router doesn't care about
the MAC.


The router knows how to take care of the situation no matter what you do
on your end.

Duane

> What if you clone your Mac adress to the router and later move
> your Nics or computers around, couldn´t that mess up the whole
> network?

That is the IP address on the wan port, so your cable provider sees the
same IP as before you put the router in. All computers behind the router
will appear to have the same IP.

A MAC address is not an IP address. The ISP doesn't see what IP address you
assign to the router, the ISP assigns the IP address to the router's WAN
interface.

Ron Bandes, CCNP, CTT+, etc.

"scram" <(E-Mail Removed)> wrote in message
news:Theoc.111766$Jy3.13525@fed1read03...
>
> > What if you clone your Mac adress to the router and later move
> > your Nics or computers around, couldn´t that mess up the whole
> > network?
>
> That is the IP address on the wan port, so your cable provider sees the
> same IP as before you put the router in. All computers behind the router
> will appear to have the same IP.

The MAC address does not come into play only during DHCP negotiation. Every
IP packet is encapsulated in an Ethernet frame that has a source MAC and a
destination MAC.

Also, you don't tell the computer to use one of the router's static IP
addresses. The router assigns a dynamic IP address to the computer from a
pool of IP addresses. It just isn't true that the router doesn't care about
the MAC.

However, the original poster needn't worry about a conflict in MAC
addresses. The TCP/IP protocol suite is layered. IP is a Network-layer
protocol that understands how to get a packet across an internetwork: from
network to network to network. But IP doesn't understand the details of how
to physically get a packet across even a single network. It's like IP is a
navigator, not a driver.

To continue the navigator/driver analogy, some networks are like roads, some
are like oceans, some are like air routes. You need different drivers to
drive cars, boats, and airplanes. These are different Data-Link Layer
protocols, like Ethernet, PPP (used on dialup), and DSL. So after IP
determines which network needs to be traversed next, it stuffs the IP packet
into a Data-Link Layer frame that is appropriate for that network type; for
your LAN that would be Ethernet. Then Ethernet takes over and "drives" the
Ethernet frame (containing the IP packet) across the LAN from your computer
to your router. Ethernet knows nothing about IP addresses, so it is using
MAC addresses to find the router on the Ethernet LAN. So on a LAN, every
interface (on both computers and routers) have both an IP address and a MAC
address. When the frame arrives at the router, the packet is removed from
the Ethernet frame and the frame is discarded. The router determines which
network the packet must traverse next. It then encapsulates the packet in a
new frame, and off we go again. Remember, not all networks are Ethernet, so
in general we can't reuse the frame. Also, the destination MAC address in
the frame is just the next destination, not the final destination. The
destination IP address in the packet is for the final destination, and it
doesn't change as the packet makes its way through many networks.

Since MAC addresses are used only to traverse a single network, and not an
internetwork, it doesn't matter if interfaces on different networks have the
same MAC address. The only reason that MAC addresses are made to be
universally unique is that the manufacturer doesn't know which two devices
will be connected to the same network. At home you have three networks in a
typical setup: your Ethernet LAN, another Ethernet between your router and
your broadband modem, and the broadband network that connects your modem to
the ISP. The router's LAN ports are on the Ethernet LAN, the router's WAN
port is on the other Ethernet between the router and the broadband modem.
It doesn't matter if the router's WAN port has the same MAC address as a
computer on the LAN because they're on different networks.

Ron Bandes, CCNP, CTT+, etc.

"Duane Arnold" <(E-Mail Removed)> wrote in message
news:Xns94E6C5B65AFE7notmenotmecoml@204.127.199.17 ...
> (E-Mail Removed) wrote in news:(E-Mail Removed):
>
> > What if you clone your Mac adress to the router and later move
> > your Nics or computers around, couldn´t that mess up the whole
> > network?
>
> NO, doing that only affects the WAN port on the router and what the ISP
> views as a valid MAC that's been provisioned and linked to your account
> that can access their ISP network.
>
> >
> > Could it not lead to two points on the network having the same
> > adress?
>
> NO, because each NIC MAC is unique and the MAC really only comes into
> play when the router is issuing DHCP IP(s) as it links the MAC to an IP
> it has issued, which is being kept and tracked by the router in the DHCP
> table. You tell the computer to use one of the router's static IP(s) and
> the MAC doesn't come into play -- period the router doesn't care about
> the MAC.
>
>
> The router knows how to take care of the situation no matter what you do
> on your end.
>
> Duane

"Ron Bandes" <RunderscoreBandes @yah00.com> wrote in
news:CQfoc.26316$(E-Mail Removed). net:

> The MAC address does not come into play only during DHCP negotiation.
> Every IP packet is encapsulated in an Ethernet frame that has a source
> MAC and a destination MAC.
>
> Also, you don't tell the computer to use one of the router's static IP
> addresses. The router assigns a dynamic IP address to the computer
> from a pool of IP addresses. It just isn't true that the router
> doesn't care about the MAC.

Well, I don't know how else to put it about the use of a static IP. As I
understood it, if the router's DHCP IP(s) started from 192.168.1.100
through 192.168.1.150 that's the pool you speak of.

Now if I wanted to use 192.168.1.2 which I understand is a static IP,
then I would have to go to the NIC's configuration screen and enter IP
192.168.1.2 subnet 255.255.255.0 and Default Gateway 192.168.1.1 (Device
IP).

I am only speaking in the context of the OP's post and the MAC and his
mis-understanding of how (basic) things were working; of course the MAC
comes into play when one looks at the picture of network traffic.

>
> However, the original poster needn't worry about a conflict in MAC
> addresses. The TCP/IP protocol suite is layered. IP is a
> Network-layer protocol that understands how to get a packet across an
> internetwork: from network to network to network. But IP doesn't
> understand the details of how to physically get a packet across even a
> single network. It's like IP is a navigator, not a driver.
>
> To continue the navigator/driver analogy, some networks are like
> roads, some are like oceans, some are like air routes. You need
> different drivers to drive cars, boats, and airplanes. These are
> different Data-Link Layer protocols, like Ethernet, PPP (used on
> dialup), and DSL. So after IP determines which network needs to be
> traversed next, it stuffs the IP packet into a Data-Link Layer frame
> that is appropriate for that network type; for your LAN that would be
> Ethernet. Then Ethernet takes over and "drives" the Ethernet frame
> (containing the IP packet) across the LAN from your computer to your
> router. Ethernet knows nothing about IP addresses, so it is using MAC
> addresses to find the router on the Ethernet LAN. So on a LAN, every
> interface (on both computers and routers) have both an IP address and
> a MAC address. When the frame arrives at the router, the packet is
> removed from the Ethernet frame and the frame is discarded. The
> router determines which network the packet must traverse next. It
> then encapsulates the packet in a new frame, and off we go again.
> Remember, not all networks are Ethernet, so in general we can't reuse
> the frame. Also, the destination MAC address in the frame is just the
> next destination, not the final destination. The destination IP
> address in the packet is for the final destination, and it doesn't
> change as the packet makes its way through many networks.
>
> Since MAC addresses are used only to traverse a single network, and
> not an internetwork, it doesn't matter if interfaces on different
> networks have the same MAC address. The only reason that MAC
> addresses are made to be universally unique is that the manufacturer
> doesn't know which two devices will be connected to the same network.
> At home you have three networks in a typical setup: your Ethernet
> LAN, another Ethernet between your router and your broadband modem,
> and the broadband network that connects your modem to the ISP. The
> router's LAN ports are on the Ethernet LAN, the router's WAN port is
> on the other Ethernet between the router and the broadband modem. It
> doesn't matter if the router's WAN port has the same MAC address as a
> computer on the LAN because they're on different networks.

I do appreciate your explaination on all of this, because I certainly
don't have this kind of in-depth knowledge in this area.

However, it's to my understanding that the modem is the device that gets
the public IP from the ISP and the first device behind the modem such as
router, a direct connect computer's NIC, or FW appliance uses the public
IP assigned to the modem --- excuse my lack of words to better describe
this.

I bring the above up because of another discussion I was having with an
OP and his mis-understanding of (excuse me for saying it *stealthing*)
the router ports and the public IP being hidden. This was based on the
Gibson Port scan and stealth check on a router where port 113 was
*closed* and not stealthed. The FTP server needed 113.

I told him it was the modem that was issued the public IP from the ISP
not the router. So, the public IP is known and that so called hiding of
the public IP meant nothing in something discovering the public IP and
stopping port scans.

Also, what's the deal with putting a dummy IP into the DMZ of the router
to redirect unsolicited inbound traffic to the dummy IP in the DMZ of the
router? Is that effective or useless? Also, I port forward port 113 to
the DMZ IP, since one port scan reported that port as being open, which I
don't have any IDENT. The scan reported back 113 was closed when I did
the forwarding.

Can you comment on it?

Duane

replace router with another and use existing cloned mac on a separate subnet
then the mac conflicts on the original network, then you just change or
clone the mac again
and then maybe ip & name #PREload into lmhosts to the original #DOM:group
to blast through the old wan's newest mac, add a route table entry....
so there's more than one way it would conflict - but its easy enuff to
change.

(E-Mail Removed) wrote:

> What if you clone your Mac adress to the router and later move
> your Nics or computers around, couldn?t that mess up the whole
> network?
>
> Could it not lead to two points on the network having the same
> adress?

Not likely, as the router port that has the cloned address, is on the other
side of the router, connected to your ISP. Nothing on your local network
will ever see that address from the router.

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.

scram wrote:

>
>> What if you clone your Mac adress to the router and later move
>> your Nics or computers around, couldn´t that mess up the whole
>> network?
>
> That is the IP address on the wan port, so your cable provider sees the
> same IP as before you put the router in. All computers behind the router
> will appear to have the same IP.
>
>

No, it's the MAC address, so that the router appears as the original
computer, to the ISP. Otherwise, you may have to get the ISP to
reprovision for the new device.


--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.