changing MAC address questions

[apngss]

I have couple questions regarding MAC address changes:

1) When we change the MAC address, it will change the firmware of NIC,
or just temporary change?
My observation is just temporary change.

2) Do you think changing MAC address can secure the machine more? I
mean at least hackers
cannot keep track on the machines that easily? Well, maybe hackers
should use IP address,
but my observation is that when I change the MAC address, IP address
will change as well.

3) I try it myself, when I change the MAC address, it will change the
IP address as well.
IP address is assigned by ISP, maybe ISP assigns the IP address based
on the MAC address
of the machine as well? MAC address identifies the network card, and IP
address identifies
the computer on the internet.

Please advise. thanks!!

 

[John Navas]

[POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]

2) Do you think changing MAC address can secure the machine more? ...

No.

 

[Chuck]

I have couple questions regarding MAC address changes:

1) When we change the MAC address, it will change the firmware of NIC,
or just temporary change?
My observation is just temporary change.

2) Do you think changing MAC address can secure the machine more? I
mean at least hackers
cannot keep track on the machines that easily? Well, maybe hackers
should use IP address,
but my observation is that when I change the MAC address, IP address
will change as well.

3) I try it myself, when I change the MAC address, it will change the
IP address as well.
IP address is assigned by ISP, maybe ISP assigns the IP address based
on the MAC address
of the machine as well? MAC address identifies the network card, and IP
address identifies
the computer on the internet.

Please advise. thanks!!

IMHE, changing your MAC address is a useless method of providing security, and
can cause worse problems.
# It is a form of Security by Obscurity.
<http://nitecruzr.blogspot.com/2005/05/security-by-obscurity.html>
# The MAC address is the lowest level identity in networking. See OSI model to
understand this
(<http://nitecruzr.blogspot.com/2005/05/security-by-obscurity.html> for
example). You absolutely must have a unique MAC address on all networked
devices. If you go changing this identity element, and cause a conflict, you
could cause yourself and other people grief.
# If you change your MAC address in an attempt to change your IP address on a
public Internet service, you could cause pain for a few people, including
another subscriber, and the ISP. Changing your IP address is another form of
Security by Obscurity.

 

[James Knott]

I have couple questions regarding MAC address changes:

1) When we change the MAC address, it will change the firmware of NIC,
or just temporary change?
My observation is just temporary change.

As far as I know, it's temporary.

2) Do you think changing MAC address can secure the machine more? I
mean at least hackers
cannot keep track on the machines that easily? Well, maybe hackers
should use IP address,
but my observation is that when I change the MAC address, IP address
will change as well.

It makes no difference for security. MAC addresses are relevant only on the
local network. They are discarded as soon as your packets pass through a
router.

3) I try it myself, when I change the MAC address, it will change the
IP address as well.
IP address is assigned by ISP, maybe ISP assigns the IP address based
on the MAC address
of the machine as well? MAC address identifies the network card, and IP
address identifies
the computer on the internet.

The ISP doesn't assign an IP address based on the MAC address. It assigns a
new address to what appears to be a new computer. It won't reassign the
previous one, until the lease expires.

 

[James Knott]

You absolutely must have a unique MAC address on all networked
devices. If you go changing this identity element, and cause a conflict,
you could cause yourself and other people grief.

The MAC only has to be unique on the local network. It's irrelevant
elsewhere.

 

[Yves Leclerc]

Answer to

1) The MAC address will/should be changed permanently in the firmware. You
need to do this only in special cases, especially when your Internet service
provider instructs you do this!

2) NO! The MAC is not a security service. Whenever the MAC changes, the
network card is told to be a different unit and another IP address is
issued. Use a firewall.

3) See complete description of answer 2. MAC address identifies the PC to
the network. ISP DHCP service locates new MAC address on their systems. IP
address does not identify your PC to the Internet. IP address provides the
"signals" so that your PC can "talk" with the Internet. The IP addresses
identifies your ISP only.

 

[Jim]

I have couple questions regarding MAC address changes:

1) When we change the MAC address, it will change the firmware of NIC,
or just temporary change?
My observation is just temporary change. Temporary.

2) Do you think changing MAC address can secure the machine more? I
mean at least hackers
cannot keep track on the machines that easily? Well, maybe hackers
should use IP address,
but my observation is that when I change the MAC address, IP address
will change as well.

No, I don't see how just changing the MAC address makes much difference.
Since the ISP only controls a range of IP addresses, all a hacker needs to
do is ping everyone of them, and try to penetrate those that respond. This
method would work whether you changed the MAC address or not.

3) I try it myself, when I change the MAC address, it will change the
IP address as well.
IP address is assigned by ISP, maybe ISP assigns the IP address based
on the MAC address
of the machine as well? MAC address identifies the network card, and IP
address identifies
the computer on the internet.

Perhaps they do. However, this is merely security by obscurity.
Jim

 

[Chuck]

(e-mail address removed) wrote:

The ISP doesn't assign an IP address based on the MAC address. It assigns a
new address to what appears to be a new computer. It won't reassign the
previous one, until the lease expires.

And if you try to connect using a MAC address currently in use by another
customer, what happens? If you appear to be an already known customer
(previously seen MAC address), will it assign the same IP address, will it
declare that IP address in use and assign another address, or wilt it declare an
unidentified problem and maybe disconnect both instances of the same MAC
address?

 

[Steve Welsh]

Since MAC addresses don't travel off the local area network, unless you
got some VLAN stuff going on, the chances are just a tiny bit small

 

[James Knott]

And if you try to connect using a MAC address currently in use by another
customer, what happens? If you appear to be an already known customer
(previously seen MAC address), will it assign the same IP address, will it
declare that IP address in use and assign another address, or wilt it
declare an unidentified problem and maybe disconnect both instances of the
same MAC address?

I suspect that would depend on the ISP.

 

[Chuck]

Since MAC addresses don't travel off the local area network, unless you
got some VLAN stuff going on, the chances are just a tiny bit small

Yup. And the smaller they are (but not zero), the longer it's gonna take your
typical clueless ISP support staff to realise that that's the cause of the
problem!

 

[kshetu]

hi!,
i chnage the mac address for my computer. but now i can not accsess the
net. what happend on mac address. i have a fixed ip.

 

[Bob I]

Ask your ISP.

 

[Tony Hwang]

hi!,
i chnage the mac address for my computer. but now i can not accsess the
net. what happend on mac address. i have a fixed ip.

Hi,
Your ISP may expect your old MAC address. Some ISP wants one registered
MAC address all the time. Talked to your ISP tech support?
My ISP does not care about MAC address.
Tony