MAC address

[Ren]

Plz any one tell me, how to change the MAC address in
win2000.

 

[Guest]

You can not change the MAC address in any operating system. MAC address is specific to the Network Interface Card connected to your system

----- Ren wrote: ----

Plz any one tell me, how to change the MAC address in
win2000

 

[David H. Lipman]

WRONG !

See my reply to the OP please...

Dave



| You can not change the MAC address in any operating system. MAC address is specific to the
Network Interface Card connected to your system.
|
| ----- Ren wrote: -----
|
| Plz any one tell me, how to change the MAC address in
| win2000.
|

 

[David H. Lipman]

Ren:

Right Click on "My Network Places" then choose "Properties"
Right Click on "Local Area Connection" then choose "Properties"
Choose "Configure"
Choose Advanced
Highlight "Network Address" and provide a 12digit Hex address, that is not a multicast
address, for the value.


Note...The above depends on the manufacturer's provided drivers. I have found most drivers
allow over-riding the hard coded MAC with another address. This included Win98, WinME and
WinXP as well.

I'm using a 3Com 3c905 and it provides the functionality I described.

Dave



| Plz any one tell me, how to change the MAC address in
| win2000.

 

[*Vanguard*]

"David H. Lipman" said in news:[email protected]:

Ren:

Right Click on "My Network Places" then choose "Properties"
Right Click on "Local Area Connection" then choose "Properties"
Choose "Configure"
Choose Advanced
Highlight "Network Address" and provide a 12digit Hex address, that
is not a multicast address, for the value.


Note...The above depends on the manufacturer's provided drivers. I
have found most drivers allow over-riding the hard coded MAC with
another address. This included Win98, WinME and WinXP as well.

I'm using a 3Com 3c905 and it provides the functionality I described.

Dave

Note that the description for that option say it is for "this adapter". If
you have a standard NIC (network interface card), the MAC is fixed. The
first part is a fixed number assigned to the NIC manufacturer while the
second half is a number assigned by that manufacturer and is supposed to be
unique. Some NIC manufacturers have decided to reuse their old addresses
but also then have to make the MAC programmable since it is possible a
customer could use a new NIC with a preprogrammed MAC address that happens
to match the MAC address of their older non-programmable NIC. If you are
using a network controller (onboard the motherboard) instead of a NIC then
the MAC is programmable.

David needs to specify if he is using a fixed (i.e., standard or old-spec)
NIC, a programmable NIC, or an onboard chipset's network controller (which
is programmable). Similary, the OP (Ren) should have mentioned what
hardware he/she is using for a NIC or the chipset providing the onboard
network controller.

 

[David H. Lipman]

*All* NICs have the MAC hard coded. As I stated, it is up to the NIC manufacturer to
provide OS drivers that can over-ride the hardware MAC with a software MAC.

I also stated it was a 3Com 3c905 BUT...I have seen the ability in numerous other cards from
Intel to Linksys to NetGear.

Dave



| "David H. Lipman" said in | > Ren:
| >
| > Right Click on "My Network Places" then choose "Properties"
| > Right Click on "Local Area Connection" then choose "Properties"
| > Choose "Configure"
| > Choose Advanced
| > Highlight "Network Address" and provide a 12digit Hex address, that
| > is not a multicast address, for the value.
| >
| >
| > Note...The above depends on the manufacturer's provided drivers. I
| > have found most drivers allow over-riding the hard coded MAC with
| > another address. This included Win98, WinME and WinXP as well.
| >
| > I'm using a 3Com 3c905 and it provides the functionality I described.
| >
| > Dave
| >
| >
| >
| > | >> Plz any one tell me, how to change the MAC address in
| >> win2000.
|
| Note that the description for that option say it is for "this adapter". If
| you have a standard NIC (network interface card), the MAC is fixed. The
| first part is a fixed number assigned to the NIC manufacturer while the
| second half is a number assigned by that manufacturer and is supposed to be
| unique. Some NIC manufacturers have decided to reuse their old addresses
| but also then have to make the MAC programmable since it is possible a
| customer could use a new NIC with a preprogrammed MAC address that happens
| to match the MAC address of their older non-programmable NIC. If you are
| using a network controller (onboard the motherboard) instead of a NIC then
| the MAC is programmable.
|
| David needs to specify if he is using a fixed (i.e., standard or old-spec)
| NIC, a programmable NIC, or an onboard chipset's network controller (which
| is programmable). Similary, the OP (Ren) should have mentioned what
| hardware he/she is using for a NIC or the chipset providing the onboard
| network controller.
|
|
| --
| ____________________________________________________________
| *** Post replies to newsgroup. E-mail is not accepted. ***
| ____________________________________________________________
|
|

 

[Bruce Chambers]

Greetings --

Unless you have a network card that allows the MAC address to be
altered, and whose manufacturer provided you a software utility to do
so, you simply replace the network card.

Bruce Chambers
--
Help us help you:



You can have peace. Or you can have freedom. Don't ever count on
having both at once. -- RAH

 

[*Vanguard*]

"David H. Lipman" said in news:%[email protected]:

*All* NICs have the MAC hard coded. As I stated, it is up to the NIC
manufacturer to provide OS drivers that can over-ride the hardware
MAC with a software MAC.

I also stated it was a 3Com 3c905 BUT...I have seen the ability in
numerous other cards from Intel to Linksys to NetGear.

Some NICs are not so hardcoded. You can reprogram their MAC using a
bootable floppy that runs their MAC address configuration utility.
Obviously this is not an OS override of the hardware or physical address but
instead is a *change* of the hardware address in the firmware on the NIC.
It is very similar to how you reprogram your BIOS (by "flashing" it).
SpeedDemon 330 NIC and Altera core chip are examples of a programmable MAC.
I'm sure there are others. If routers can clone MAC addresses or let you
specify one to program into it then obviously NICs could perform the same
task by "flashing" the firmware stored in their EEPROM, too.

If you run "arp -d *" on host_B and then use the OS override option on
host_A for the MAC address and, say, define the MAC address as
xx-xx-xx-nn-nn-nn which is different than its hardware address of
xx-xx-xx-rr-rr-rr, and then connect to another host_B in your workgroup,
what does "arp -a" on host_B report for the MAC address of host_A? Does
host_B's arp report show the hardware or OS configured MAC address for
host_A?

Even if the above scenario works to report the OS-specified MAC address for
host_A as seen by host_B, that only applies in Windows. If the NIC's MAC
address is programmable, that's what you would see when connecting under an
OS or with drivers that don't have the software override.

Until today, I didn't know about the "software MAC" override provided by
Windows. Learn something every day.

"... provide a 12digit Hex address, that is not a multicast address, for the
value."

How can a 48-bit MAC address equate to an multicast IP address (32 bits for
IPv4, 128 bits for IPv6)? Is the definition of a multicast address, "The
least significant bit of the most significant byte of a multi-cast address
is one"? At what point to the bits align between the 48-bit MAC and the 32-
or 128-bit IP address?

 

[David H. Lipman]

Granted there may be some NICs that have programmable MAC adddreses, however I think that
Routers that use the "clone MAC address" concept use a sofware over-ride as well. Take the
Linksys BEFSR41 and BEFSR81 Cable/DSL Routers. They use COTS (Common Off The Shelf)
RealTek 8129 chip-sets which I now have fixed not programmable MAC addresses. Just
resetting the modem to factory defaults will reload the hard coded MAC address.

Multicast IP and Multicast MAC work similarly but are different.
For exmple, Symantec Ghost Enterprise uses Multicast IP addresses;
224.0.2.0-239.255.255.255
Synoptic/BayNetworks/Nortel Equipment uses the Multicast MAC address "00-00-81-00-00-00" to
find their respective hardware on LAN and will use "01-00-81-00-01-00" for communicating
together. One reason they might use multicast addressing is for the Spanning Tree Protocol
(STP), another is for Routing protocols.

Example MAC Multi-Casting addresses
"00-00-81-00-00-00","Synoptics_MCast"
"01-00-81-00-01-00","Synoptics_NMM_MCast"
"01-00-5E-00-01-7F","XEROX-DEVICE-DISCOVERY"
"01-00-5E-00-00-01","ALL-SYSTEMS.MCast"
"01-00-0C-CC-CC-CC","CISCO-CDP/VTP"
"01-00-0C-CC-CC-CC","CISCO_MCast"
"01-00-5E-00-00-FB","mDNS"
"01-00-5E-00-00-09","RIP2-ROUTERS"
"01-00-0C-00-00-00","SNAP-0x0003"
"01-00-0C-EE-EE-EE","SNAP-0x2006"
"01-80-C2-00-00-00","STP-MCast-for-bridges"

I suspect that if PC1 had MAC "A" and was over-ridden with MAC "B" then it would not
communicate with other hardware until the MAC cached-out of their respective ARP caches.

The following is a URL on IP multicast addressing:
http://darkwing.uoregon.edu/~llynch/mcastwks/shep/address/img0.htm

The folowing URLs have information on MAC multicasting:
http://www.oreillynet.com/pub/a/network/2001/08/10/net_2nd_lang.html




| "David H. Lipman" said in | > *All* NICs have the MAC hard coded. As I stated, it is up to the NIC
| > manufacturer to provide OS drivers that can over-ride the hardware
| > MAC with a software MAC.
| >
| > I also stated it was a 3Com 3c905 BUT...I have seen the ability in
| > numerous other cards from Intel to Linksys to NetGear.
|
| Some NICs are not so hardcoded. You can reprogram their MAC using a
| bootable floppy that runs their MAC address configuration utility.
| Obviously this is not an OS override of the hardware or physical address but
| instead is a *change* of the hardware address in the firmware on the NIC.
| It is very similar to how you reprogram your BIOS (by "flashing" it).
| SpeedDemon 330 NIC and Altera core chip are examples of a programmable MAC.
| I'm sure there are others. If routers can clone MAC addresses or let you
| specify one to program into it then obviously NICs could perform the same
| task by "flashing" the firmware stored in their EEPROM, too.
|
| If you run "arp -d *" on host_B and then use the OS override option on
| host_A for the MAC address and, say, define the MAC address as
| xx-xx-xx-nn-nn-nn which is different than its hardware address of
| xx-xx-xx-rr-rr-rr, and then connect to another host_B in your workgroup,
| what does "arp -a" on host_B report for the MAC address of host_A? Does
| host_B's arp report show the hardware or OS configured MAC address for
| host_A?
|
| Even if the above scenario works to report the OS-specified MAC address for
| host_A as seen by host_B, that only applies in Windows. If the NIC's MAC
| address is programmable, that's what you would see when connecting under an
| OS or with drivers that don't have the software override.
|
| Until today, I didn't know about the "software MAC" override provided by
| Windows. Learn something every day.
|
| "... provide a 12digit Hex address, that is not a multicast address, for the
| value."
|
| How can a 48-bit MAC address equate to an multicast IP address (32 bits for
| IPv4, 128 bits for IPv6)? Is the definition of a multicast address, "The
| least significant bit of the most significant byte of a multi-cast address
| is one"? At what point to the bits align between the 48-bit MAC and the 32-
| or 128-bit IP address?
|
|

 

[*Vanguard*]

Thanks for the links. I've saved them on my desktop until I get time in a
couple from now to read them.