UNSOLVED

ikp

updated

22 years ago

I

ikp

5 Posts

0

9071

November 11th, 2004 23:00

How to block computers with unknow MACs

Hi,

I tried to configure a Dell 3324 switch this way:

...
interface ethernet 1/e1
port security discard-shutdown
exit
interface vlan 1
bridge address 00:08:74:13:bb:eb ethernet 1/e1 secure
exit
exit
...

The idea is to shutdown the port at any atempt to hook up a computer that has no known MAC to me (switch).

But when I do this, the port does not shutdown as I want.

The case is this: configure the switch, use the known MAC computer, no problems. Disconnect. Connect an unknown MAC computer to the port, and never send a packet to the switch from this unknow computer. This computer will receive all the broadcast traffic in the nertwork, something I don't want to happen. This will keep going on as far as the unknown computer does not send any packet.

How can I configure the switch in a way that it will pass traffic to the computer only if the computer transmits first, so the that the switch can know which MAC is plugged there?

Is there a way to achieve this, or something similar. My problem is simple, a in-use port connected to a listen-only computer sniffing broadcast traffic. As windoses generate a lot of it for SMB protocol, as normal ARPs, we don't want an attacker listening to our broadcast traffic. We don't have any IP multicast traffic.


Also, a related question. Is there a way to auto-re-enable a shutdown port? Sort of if someone plugs a computer in the wrong plug, that by simple replug of the right one things work again.



Thanks,

Ivan