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New Member

pc same address as a router

Hello

We have just had someone type the ip address of the gateway as the ip address of a pc, this resulted in an entire subnet going down until we found the pc and shut down the port. Is there any way to prevent this apart from using dhcp etc. Thanks

4 REPLIES
New Member

Re: pc same address as a router

There is no practical way to do this, even if you use DHCP. Someone could still hardcode their interface with an IP address at any time.

The only thing that comes to mind (remember, this isn't *practical*) is to add static ARP entries to every single computer on your network with the MAC/IP address of the default gateway. This might be accomplished with a login script issuing the command:

arp -s 157.55.85.212 00-aa-00-62-c6-09

Mick.

Cisco Employee

Re: pc same address as a router

You can configure policies on the Operating System to prevent users from changing the IP address.

New Member

Re: pc same address as a router

From the network point-of-view, you cannot do anything.

JPL.

New Member

Re: pc same address as a router

You can add a permenant arp entry for the routers in all stations, you can do it automatcally bu using an automatic logon script.

> arp -s -p ip_address mac_address

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