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Re: 2 NIC and arpwatch

On Fri, Sep 12, 2003 at 10:32:37PM +0200, Leonardo Boselli wrote:
> Technically both nics are on the same physical [switched] network.
> the problem: another machine running arpwatch show me every 10 
> minutes the address as flipping between the two nics ...
> (while the routing works fine !).
> Does someone have an idea on what is happeeninmg and how to fix it ?

The kernel is answering requests for it's local ip addresses on both
interfaces. This means, that it is using 2 different MACs for two differen
IPs, which is detected by arpwatch.

What you can do is turn off ip-forwarding (of possible) and/or configure the
kernel not to answer on the "wrong" interface. The simples way to achiev
this is to filter incoming ARP request packets with iptables (based on
interface name and requested address). 

There are also arp filter and silent arp patches out there.

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