[nSLUG] Re: MAC-address/router question

Rich budman85 at eastlink.ca
Sat Dec 10 20:03:51 AST 2005


On Fri, 2005-12-09 at 04:43 -0400, Mike Spencer wrote:
> > SunOS/Solaris and Linux can assign any MAC to any network device.
> 
> What would I read to learn about this?  About how this is done?
> 

Dop explained it very well.  Thanks. :)

I only played around with it once at work replacing an old nic in one of
the Sun machines.  Changing the mac is not permanent, the address will
revert back if system is reset.  May need to add in the bootup scripts.



> Either I'm only partially getting this or I know something that ain't
> so.  If a device comes out of the box with a MAC address printed on
> it, I infer that it's coded in the hardware.  As well, I infer from
> /etc/rc.d/rc.wireless.conf that some bits of the MAC address identify
> the mfgr/vendor which in turn implies a hard-coded value.  Do you mean
> by "assign any MAC", creating a virtual or spoofed MAC address known
> to the OS and mapped by the OS onto the "real", hard-coded MAC?  I
> don't quite see how that would work.
> 

Yes, the sticker you see is the factory address assigned.
Its like a serial number, each ethernet address is registered or
maintained by that vendor.  I think its the first 6 hex digits are the
vendor id.  

> 
> > The cable modem should have its own MAC.
> > The router should have a WAN and LAN MAC address.
> > If its wireless add another MAC for WLAN.
> > ....
> > Was this a new router?  if not , maybe it was an prior config.
> 
> No. D-Link DI-713P (DL-713P?) from a junk bin.  Has 3 ethernet ports,
> WAN port, "com" port, printer port and antennae.  And there's no
> cable connection, not a cable router, I'm too far off the beaten path
> to have cable.  I do dialup via an external modem connected to a
> desktop computer, not via the router.  The router just makes it
> possible to move stuff between 3 boxen in the house and 1 in the shop.
> 

I used to have a Linux box dialer, I think it was DailD I used to
maintain the dailup connection.  I had many discussions with admins at
the local provider, they thought I was hogging bandwidth. 

hehe, I told them I set the modem to timeout if no activity after 20min,
thing is there was always someone on at different times of the day.  I
think I used to have only a 4-6 hr idle time. hehe.  At that time, I had
a 4 port dumb hub.  Worked fine for 3 computers and a firewall.

I wanted to try tie two modems together to get more bandwidth, but the
provider would only go for it if I paid for another account. :)


> 
> Well, I think my question is answered, regardless of the matter of
> changing a MAC. Separate functions/modalities of the router have
> separate hardware devices and thus separate MAC addresses.
> 
> Thanks,
> - Mike

Sure.  Hope it helped. 


Rich

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