Re: changing MAC address questions

On 10 Oct 2005 15:03:03 -0500, Chuck <none@xxxxxxxxxxx> wrote:

>What happens if you change it, and cause a conflict with another ISP customer?

There are three MAC addresses that you can control. Kindly specify
which one you want to play with.
1. The WAN side MAC address. This is what the ISP uses to assign an
IP address for the ARP table. Every time you change this MAC address,
the DHCP server thinks it's a new computer and will assign a new IP
address. This will drive your ISP nuts. If you duplicate a MAC
address in use at the ISP, your traffic will either stop or get
screwed up. It will also trigger an alarm if they have arpwatch or
some other duplicate MAC/IP address daemon running.

2. The MAC address of your computer on your LAN assuming you have a
router. This can be temporarily changed with a registry tweak. It
does nothing useful as this MAC address is not seen on the internet.
Changing it will temporarily screw up your LAN ARP table but that can
be fixed with:
apr -d your_LAN_IP_address

3. The MAC address of the wireless access point in side your wireless
router. This will cause some confusion to attackers as programs such
as Netstumbler will think there are multiple access points. However,
the same thing will happen to valid wireless users.

>Some ISPs that do dynamic addressing hash the MAC address to derive IP address.

Ummm.... none that I know about.

>BTW, posting your email address openly will get you more unwanted email, than
>wanted email. Learn to munge your email address properly, to keep yourself a
>bit safer when posting to open forums. Protect yourself and the rest of the
>internet - read this article.

Have you verified that as true? I have 3 mailboxes that I have used
since the stone age of the internet (when it was all Usenet, there was
no web, and everything ran on Telebit modems with UUCP). I have never
bothered to mung, mutilate, or otherwise hide my email addresses. I
get no more junk email than any of my friends and accomplises that go
through rediculous exercises to avoid the spammers. If you want to
get rid of spam, start here:
and take out a few of these turkeys.

Jeff Liebermann jeffl@xxxxxxxxxxxxxxxxxxxxxx
150 Felker St #D
Santa Cruz CA 95060
Skype: JeffLiebermann AE6KS 831-336-2558