Fwd: RE: ARP responses broken!

Bingner Sam J. Contractor RSIS
2001-04-17T18:13:05Z

****** Forwarded Message Follows *******
>To: "'Christopher Friesen'" <cfriesen@nortelnetworks.com>, Sampsa Ranta
<sampsa@netsonic.fi>
>From: "Bingner Sam J. Contractor RSIS" <Sam.Bingner@hickam.af.mil>
>Date: Tue, 17 Apr 2001 18:07:41 -0000
>
>I tested this with kernel version 2.2.18 and arp_filter appeared to be
>broken... I enabled it for /proc/sys/net/ipv4/conf/all/arp_filter,
>/proc/sys/net/ipv4/conf/eth0/arp_filter and
>/proc/sys/net/ipv4/conf/eth1/arp_filter and it did not change the arp
>behavior at all. I enabled hidden and it worked, is there a know problem
>with this functionality?
>
> Sam Bingner
> PACAF CSS/SCHE
> Contractor RSIS
> DSN 315 449-7889
> COMM 808 449-7889
>
>
>-----Original Message-----
>From: Christopher Friesen [mailto:cfriesen@nortelnetworks.com]
>Sent: Tuesday, April 17, 2001 4:25 AM
>To: Sampsa Ranta
>Cc: linux-net; linux-kernel
>Subject: Re: ARP responses broken!
>
>
>Sampsa Ranta wrote:
>
>> I have two interfaces that share same subnet, I call eth0 194.29.192.37
>> and eth1 194.29.192.38. I have forwarding turned on, proxy arp is not
>> neighter are redirects.
>>
>> When I flush local neighbor table in other machine I use to observe the
>> response and ping the router I get response like:
>>
>> 23:38:25.278848 > arp who-has 194.29.192.38 tell 194.29.192.10
>(0:50:da:82:ae:9f)
>> 23:38:25.278988 < arp reply 194.29.192.38 is-at 0:1:2:dc:d2:64
>(0:50:da:82:ae:9f)
>> 23:38:25.279009 < arp reply 194.29.192.38 is-at 0:1:2:dc:d2:6c
>(0:50:da:82:ae:9f)
>>
>> The second one is the valid one, but both interfaces seem to answer to the

>> broadcasted packet with their own ARP addresses.
>
>This is the default Linux behaviour. It can be turned off by running the
>following command as root:
>
>echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter
>
>This ensures that interfaces will only respond to arp requests for IP
>addresses
>which are configured as belonging to that particular interface.
>
>Chris
>
>--
>Chris Friesen | MailStop: 043/33/F10
>Nortel Networks | work: (613) 765-0557
>3500 Carling Avenue | fax: (613) 765-2986
>Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com
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