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Old 04-26-2007, 11:45 AM   #1
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Registered: Apr 2007
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Unhappy two nics on one subnet on one machine


I`ve configured a machine with 2 physical nics witch both are attached to the same subnet.
They both have a different ip address ( in the same subnet ).
But when I do an arp request from a second machine for the ip adres of one of nics on the first machine I get a reply of both interfaces on the machine .

Does anybody know why this is happening ?

Thanks in advance for the answer.

Old 04-27-2007, 06:40 AM   #2
Registered: Mar 2006
Distribution: RedHat, Slackware, Experimenting with FreeBSD
Posts: 222

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Are you getting two different MAC addresses or the same MAC address?

Also what is the output of this on your system:

cat /proc/sys/net/ipv4/conf/eth0/proxy_arp
cat /proc/sys/net/ipv4/conf/eth1/proxy_arp
Old 04-27-2007, 07:28 AM   #3
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Registered: Apr 2007
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I found the solution myself.

If two interfaces are on the same subnet they both answer arp requests ( with their own mac ) for the ip adress that just is configured on one of the cards.

This behaviour can be stopped by setting :

echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter


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