comp.os.linux.networking
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Re: security of IP address

Subject: Re: security of IP address
From: glen herrmannsfeldt
Date: Tue, 03 May 2005 14:11:00 -0700
Newsgroups: comp.protocols.tcp-ip, comp.os.linux.networking
Barry Margolin wrote:

(snip)

I think you misunderstood the question. He's not asking about security during the DHCP process. He wanted to know about what happens after an IP has been assigned to a host -- can the router continuously verify that the MAC that's using an IP is the one to which the IP was assigned?

Not if there is another router in between.

BTW, to the OP -- did you know that most NICs provide the ability to change the MAC? So verifying MACs doesn't really provide all that much security.

As far as I know, all do, though the software to do it
isn't always supplied.

In the olden days, it wasn't easy to put PROM on the same
chip as the ethernet control, so it depends on the driver
reading the PROM (or EPROM or EEPROM) and writing to the
appropriate register.

Also, some protocols (DECNet for one) require setting the MAC
based on the host address.

It might be that some now have the EEPROM on the same chip,
but the ability to use protocols like DECNet will still require
the ability to set the MAC address.

-- glen


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