Re: BUG: 2 NICs on same network

From: Denis Vlasenko (vda@port.imtp.ilyichevsk.odessa.ua)
Date: Tue Apr 23 2002 - 11:05:02 EST


On 23 April 2002 07:39, Frank Louwers wrote:
> Hi,
>
> We recently stummed across a rather annoying bug when 2 nics are on
> the same network.
>
> Our situation is this: we have a server with 2 nics, each with a
> different IP on the same network, connected to the same switch. Let's
> assume eth0 has ip 1.2.3.1 and eth1 has 1.2.3.2, with a both with a
> netmask of 255.255.255.0.
>
> Now the strange thing is that traffic for 1.2.3.2 arrives at eth0 no
> matter what!
>
> Even if we disconnect the cable for eth1, 1.2.3.2 still replies to
> pings, ssh, web, ...
>
> We tested this on IA32 architecture, different 2.4.x kernels and
> different nics ...
>
> Is this a bug or a known issue? If it is not a bug, how can it be
> solved?

Do you have ip forwarding enabled? If yes, kernel just forwards packets:
network -> eth0 -> kernel

Try traceroute to eth1' ip. Examine arp tables. What MAC is listed there for
eth1 IP?

--
vda
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