> But each device must have a unique address.
... within a single Ethernet. As soon as there's a router in the
way, MAC addresses generally no longer have to be unique - because
they're not passed on.
Changing MAC address
Started by ●January 11, 2006
Reply by ●January 11, 20062006-01-11
Reply by ●January 11, 20062006-01-11
We manufacture Rabbit SBC's and have purchased a MAC address range.
All our products get an 'X-Graph' MAC address. To reduce programming
time in production we developed a factory program which is downloaded
via SPI (not the slow RS232C). To do this we made our own bootloader,
BIOS and factory software. Also the MAC address is auto-programmed.
The following is part of the code we use:
MAC[0] = 0x00;
MAC[1] = 0x00;
MAC[2] = 0x00;
MAC[3] = 0x00;
MAC[4] = 0x00;
MAC[5] = 0x00;
memcpy(SysIDBlock.macAddr, MAC, 6);
SysIDBlock.idBlockCRC = 0x0000;
k = (int)(&SysIDBlock.reserved) - (int)(&SysIDBlock.tableVersion);
crc = calcCRC(0x0000, &SysIDBlock, k);
crc = calcCRC(crc, &SysIDBlock.idBlockSize, 16);
SysIDBlock.idBlockCRC = crc;
k = writeIDBlock();
The writeIDBlock() and calcCRC() functions you can find in
write_idblock.c.
Sucess,
Rudi
www.x-graph.be the next generation Rabbit SBC with (TFT Color) LCD
--- In rabbit-semi@rabb..., "ttt_raquel" <rribagorda@t...> wrote:
>
> Hi all.
>
> I work for a Spanish company and we develop our equipments using
> RCM2200 and RCM2250 core modules as our processor. We would like to
> give these equipments our own MAC address, so I would like to know if
> it is possible (legally) and how to change the MAC address properly. Is
> it necessary to use the write_idblock.c function? In this case, which
> is the last version compatible with DC9.21?
>
> Thank you very much for your replies.
>
All our products get an 'X-Graph' MAC address. To reduce programming
time in production we developed a factory program which is downloaded
via SPI (not the slow RS232C). To do this we made our own bootloader,
BIOS and factory software. Also the MAC address is auto-programmed.
The following is part of the code we use:
MAC[0] = 0x00;
MAC[1] = 0x00;
MAC[2] = 0x00;
MAC[3] = 0x00;
MAC[4] = 0x00;
MAC[5] = 0x00;
memcpy(SysIDBlock.macAddr, MAC, 6);
SysIDBlock.idBlockCRC = 0x0000;
k = (int)(&SysIDBlock.reserved) - (int)(&SysIDBlock.tableVersion);
crc = calcCRC(0x0000, &SysIDBlock, k);
crc = calcCRC(crc, &SysIDBlock.idBlockSize, 16);
SysIDBlock.idBlockCRC = crc;
k = writeIDBlock();
The writeIDBlock() and calcCRC() functions you can find in
write_idblock.c.
Sucess,
Rudi
www.x-graph.be the next generation Rabbit SBC with (TFT Color) LCD
--- In rabbit-semi@rabb..., "ttt_raquel" <rribagorda@t...> wrote:
>
> Hi all.
>
> I work for a Spanish company and we develop our equipments using
> RCM2200 and RCM2250 core modules as our processor. We would like to
> give these equipments our own MAC address, so I would like to know if
> it is possible (legally) and how to change the MAC address properly. Is
> it necessary to use the write_idblock.c function? In this case, which
> is the last version compatible with DC9.21?
>
> Thank you very much for your replies.
>
Reply by ●January 11, 20062006-01-11
Thanks
for that clarification. But...don't you have the same potential problem
as you do when if you create your own MAC addresses? As long as you are
on your own private network (behind a router?) you can use any MAC you
want. But should the equipment ever be used on a public network you
could have problems? And who knows how a customer will try to use your
equipment?
----- Original Message ----
From: Don Starr <d...@starrsoft.com>
To: r...@yahoogroups.com
Sent: Wednesday, January 11, 2006 09:59:25
Subject: RE: [rabbit-semi] Changing MAC address
> But each device must have a unique address.
... within a single Ethernet. As soon as there's a router in the
way, MAC addresses generally no longer have to be unique - because
they're not passed on.
----- Original Message ----
From: Don Starr <d...@starrsoft.com>
To: r...@yahoogroups.com
Sent: Wednesday, January 11, 2006 09:59:25
Subject: RE: [rabbit-semi] Changing MAC address
> But each device must have a unique address.
... within a single Ethernet. As soon as there's a router in the
way, MAC addresses generally no longer have to be unique - because
they're not passed on.
Reply by ●January 11, 20062006-01-11
> Thanks for that clarification. But...don't you have the same
potential
> problem as you do when if you create your own MAC addresses? As long as
> you are on your own private network (behind a router?) you can use any
> MAC you want. But should the equipment ever be used on a public network
> you could have problems? And who knows how a customer will try to use
> your equipment?
If you're connecting any device directly to a public network, and the
connection method allows MAC addresses through (e.g. a Level 2 bridge),
you're asking for all kinds of trouble, anyway. The fact that your MAC
address might be duplicated somewhere in the world is (or should be)
the least of your worries. All of your broadcast traffic is now on some
part of that public network, and anybody on that "part" can now send
directed traffic at your device.
(Exceptions, of course, for devices that are _designed_ to be connected
to the public network, like routers themselves.)
> problem as you do when if you create your own MAC addresses? As long as
> you are on your own private network (behind a router?) you can use any
> MAC you want. But should the equipment ever be used on a public network
> you could have problems? And who knows how a customer will try to use
> your equipment?
If you're connecting any device directly to a public network, and the
connection method allows MAC addresses through (e.g. a Level 2 bridge),
you're asking for all kinds of trouble, anyway. The fact that your MAC
address might be duplicated somewhere in the world is (or should be)
the least of your worries. All of your broadcast traffic is now on some
part of that public network, and anybody on that "part" can now send
directed traffic at your device.
(Exceptions, of course, for devices that are _designed_ to be connected
to the public network, like routers themselves.)
Reply by ●January 11, 20062006-01-11
First: we should ALL remember that the FBI and other Cyber Security
agencies use the MAC address to prosicute child porn cases. the MAC and
the associated ISP are unique to each case. To find any MAC and ISP
routed packet present on the same network would cause 1000's of
problems to the security.
There should NEVER be a reason to change a MAC address on any networked device.
If you are trying to setup a privite network with a sequencial MAC numbering system to insure security, then you would be better served to control the Intranet IP address assignments which is easily controlled, along with the SNM for grouping.
My 2cents! :-)
JIMA
Don Starr wrote:
There should NEVER be a reason to change a MAC address on any networked device.
If you are trying to setup a privite network with a sequencial MAC numbering system to insure security, then you would be better served to control the Intranet IP address assignments which is easily controlled, along with the SNM for grouping.
My 2cents! :-)
JIMA
Don Starr wrote:
> Thanks for that clarification. But...don't you have the same potential > problem as you do when if you create your own MAC addresses? As long as > you are on your own private network (behind a router?) you can use any > MAC you want. But should the equipment ever be used on a public network > you could have problems? And who knows how a customer will try to use > your equipment? If you're connecting any device directly to a public network, and the connection method allows MAC addresses through (e.g. a Level 2 bridge), you're asking for all kinds of trouble, anyway. The fact that your MAC address might be duplicated somewhere in the world is (or should be) the least of your worries. All of your broadcast traffic is now on some part of that public network, and anybody on that "part" can now send directed traffic at your device. (Exceptions, of course, for devices that are _designed_ to be connected to the public network, like routers themselves.) -------- YAHOO! GROUPS LINKS --------No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.14.17/226 - Release Date: 1/10/2006
Reply by ●January 11, 20062006-01-11
I’ve heard of people that have taken obsolete NIC cards and taken their MAC address for their own custom hardware. Granted the MAC manufacture ID won’t make sense but it was unique and valid when you are the one holding the original card it came from.
Ryan
From:
r...@yahoogroups.com
[mailto:r...@yahoogroups.com]
On Behalf Of IDES
Sent: Wednesday, January 11, 2006
4:51 PM
To:
r...@yahoogroups.com
Subject: Re: [rabbit-semi]
Changing
MAC address
First: we should ALL remember that the FBI and other
Cyber Security agencies use the MAC address to prosicute child porn cases. the
MAC and the associated ISP are unique to each case. To find any MAC and
ISP routed packet present on the same network would cause 1000's of
problems to
the security.
There should NEVER be a reason to change a MAC address on any networked
device.
If you are trying to setup a privite network with a sequencial MAC numbering
system to insure security, then you would be better served to control the
Intranet IP address assignments which is easily controlled, along with the SNM
for grouping.
My 2cents! :-)
JIMA
Don Starr wrote:
Reply by ●January 11, 20062006-01-11
> First: we should ALL remember that the FBI and other Cyber Security
> agencies use the MAC address to prosicute child porn cases. the MAC
> and the associated ISP are unique to each case. To find any MAC and
> ISP routed packet present on the same network would cause 1000's of
> problems to the security.
Perhaps you're thinking of IP addresses, not MAC addresses. In many
(most?) cases, MAC addresses aren't passed onto the public network;
they stay within the local network. For example, no MAC address on
my LAN ever leaves my LAN.
MAC addresses would be almost useless in prosecution, anyway, given
that they're so easily changed.
> agencies use the MAC address to prosicute child porn cases. the MAC
> and the associated ISP are unique to each case. To find any MAC and
> ISP routed packet present on the same network would cause 1000's of
> problems to the security.
Perhaps you're thinking of IP addresses, not MAC addresses. In many
(most?) cases, MAC addresses aren't passed onto the public network;
they stay within the local network. For example, no MAC address on
my LAN ever leaves my LAN.
MAC addresses would be almost useless in prosecution, anyway, given
that they're so easily changed.
Reply by ●January 11, 20062006-01-11
>There should NEVER be a reason to change a MAC address on any networked
>device.
There are several good reasons why someone would change the MAC address.
First of all, MAC address ranges can be purchased. If I purchased my own
range of MAC addresses and I want to use them, I should. If I am making my
own rabbit boards, they do not come with their own MAC address and I would
have to set the MAC address.
Also, there are several good reasons to duplicate a MAC address. It may be
neccessary to replace a piece of network equipment with a custom module.
Some proprietary hardware uses fixed MAC addresses and this would be the
only way of replacing that equipment. Perhaps you are testing network
security via intercepting packets intended for a certain MAC.
I know of several network admins who lock each port on their managed
switches to a certain MAC address. If a NIC goes out and needs to be
replaced while the network admin is not around to update the switch, or if
he has lost the password, etc the NIC can be forced to a certain MAC
address. This setting is available in many drivers and linux.
As others have pointed out, MACs do leave networks. Routers route IP
traffic only. If you have a router separating your network from the world
then you can do whatever you want with the MACs on your network equipment.
You should however probably make sure you don't conflict with MACs on your
own network. They run on equipment you own and/or designed. If you want to
have sequential MACs, encode some data into the MAC, etc, it is up to you. -Aaron > --- Ursprgliche Nachricht ---
> Von: IDES <jima@jima...>
> An: rabbit-semi@rabb...
> Betreff: Re: [rabbit-semi] Changing MAC address
> Datum: Wed, 11 Jan 2006 16:51:16 -0600
>
>First: we should ALL remember that the FBI and other Cyber Security
>agencies use the MAC address to prosicute child porn cases. the MAC and
>the associated ISP are unique to each case. To find any MAC and ISP
>routed packet present on the same network would cause 1000's of problems
>to the security.
>There should NEVER be a reason to change a MAC address on any networked
>device.
>If you are trying to setup a privite network with a sequencial MAC
>numbering system to insure security, then you would be better served to
>control the Intranet IP address assignments which is easily controlled,
>along with the SNM for grouping.
>My 2cents! :-)
>JIMA
--
Lust, ein paar Euro nebenbei zu verdienen? Ohne Kosten, ohne Risiko!
Satte Provisionen f GMX Partner: http://www.gmx.net/de/go/partner
>device.
There are several good reasons why someone would change the MAC address.
First of all, MAC address ranges can be purchased. If I purchased my own
range of MAC addresses and I want to use them, I should. If I am making my
own rabbit boards, they do not come with their own MAC address and I would
have to set the MAC address.
Also, there are several good reasons to duplicate a MAC address. It may be
neccessary to replace a piece of network equipment with a custom module.
Some proprietary hardware uses fixed MAC addresses and this would be the
only way of replacing that equipment. Perhaps you are testing network
security via intercepting packets intended for a certain MAC.
I know of several network admins who lock each port on their managed
switches to a certain MAC address. If a NIC goes out and needs to be
replaced while the network admin is not around to update the switch, or if
he has lost the password, etc the NIC can be forced to a certain MAC
address. This setting is available in many drivers and linux.
As others have pointed out, MACs do leave networks. Routers route IP
traffic only. If you have a router separating your network from the world
then you can do whatever you want with the MACs on your network equipment.
You should however probably make sure you don't conflict with MACs on your
own network. They run on equipment you own and/or designed. If you want to
have sequential MACs, encode some data into the MAC, etc, it is up to you. -Aaron > --- Ursprgliche Nachricht ---
> Von: IDES <jima@jima...>
> An: rabbit-semi@rabb...
> Betreff: Re: [rabbit-semi] Changing MAC address
> Datum: Wed, 11 Jan 2006 16:51:16 -0600
>
>First: we should ALL remember that the FBI and other Cyber Security
>agencies use the MAC address to prosicute child porn cases. the MAC and
>the associated ISP are unique to each case. To find any MAC and ISP
>routed packet present on the same network would cause 1000's of problems
>to the security.
>There should NEVER be a reason to change a MAC address on any networked
>device.
>If you are trying to setup a privite network with a sequencial MAC
>numbering system to insure security, then you would be better served to
>control the Intranet IP address assignments which is easily controlled,
>along with the SNM for grouping.
>My 2cents! :-)
>JIMA
--
Lust, ein paar Euro nebenbei zu verdienen? Ohne Kosten, ohne Risiko!
Satte Provisionen f GMX Partner: http://www.gmx.net/de/go/partner
Reply by ●January 11, 20062006-01-11
Changing the MAC address of most modern devices is trivial depending on your
OS. FreeBSD and Linux both let you do it from ifconfig. I seem to remember that
the XP driver for my Marvell GigEth lets me change the MAC as well. Note that
these methods don't change the power-up MAC, but let you change the MAC at
run time.
My employer changes the default (power-up) MAC on the hardware we resell to (a) use our OUI so that people dumping the traffic can tell it comes from our appliance and to (b) encode the unit's serial number and to (c) encode which ethernet device is which since the software can number the interfaces differently from one OS revision to the next.
We change the default MAC address using a program supplied by our motherboard manufacturer, but they seem to have received it from Intel. Aside from having to boot the box from a floppy, it works fine.
Kelly
My employer changes the default (power-up) MAC on the hardware we resell to (a) use our OUI so that people dumping the traffic can tell it comes from our appliance and to (b) encode the unit's serial number and to (c) encode which ethernet device is which since the software can number the interfaces differently from one OS revision to the next.
We change the default MAC address using a program supplied by our motherboard manufacturer, but they seem to have received it from Intel. Aside from having to boot the box from a floppy, it works fine.
Kelly
Reply by ●January 12, 20062006-01-12
Isn't the MAC Address unique by definition
(or supposed to be). Further, there are many devices you may not have
thought also have a MAC Address, like Cable Modems, Satellite Receivers, Set-Top
boxes etc. I have been involved in "Clean-up" of problems created by
someone who inadvertently got an address index wrong. The result is a huge
problem that is not easy to find.
Controlling the address for a few hundred
devices is not difficult. But over time, with a very large address
population, it is a major deal. Imagine the poor guys that share a common
MAC address in a large Cable System. Cust(1) turns has HBO turned
off. Cust(2) calls and complains because his HBO was turned off...Customer
Service turns it back on. Do you think Cust(1) is going to complain about
receiving HBO for FREE...?
Rich
----- Original Message -----From: IDESTo: r...@yahoogroups.comSent: Wednesday, January 11, 2006 2:51 PMSubject: Re: [rabbit-semi] Changing MAC addressFirst: we should ALL remember that the FBI and other Cyber Security agencies use the MAC address to prosicute child porn cases. the MAC and the associated ISP are unique to each case. To find any MAC and ISP routed packet present on the same network would cause 1000's of problems to the security.
There should NEVER be a reason to change a MAC address on any networked device.
If you are trying to setup a privite network with a sequencial MAC numbering system to insure security, then you would be better served to control the Intranet IP address assignments which is easily controlled, along with the SNM for grouping.
My 2cents! :-)
JIMA
Don Starr wrote:> Thanks for that clarification. But...don't you have the same potential > problem as you do when if you create your own MAC addresses? As long as > you are on your own private network (behind a router?) you can use any > MAC you want. But should the equipment ever be used on a public network > you could have problems? And who knows how a customer will try to use > your equipment? If you're connecting any device directly to a public network, and the connection method allows MAC addresses through (e.g. a Level 2 bridge), you're asking for all kinds of trouble, anyway. The fact that your MAC address might be duplicated somewhere in the world is (or should be) the least of your worries. All of your broadcast traffic is now on some part of that public network, and anybody on that "part" can now send directed traffic at your device. (Exceptions, of course, for devices that are _designed_ to be connected to the public network, like routers themselves.) -------- YAHOO! GROUPS LINKS --------No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.14.17/226 - Release Date: 1/10/2006
