Re: Arp problem

[Ben Greear <greearb@candelatech.com>]

Chris Friesen wrote:
> 
> Sourav Sen wrote:
> >
> > Hi,
> >         I have a machine with multiple network cards with different IP
> > addresses assigned. All are in the same network (I need this for
> > whatever reason). But when a arp request
> > appears on the wire for any of these IP addresses, all the interfaces go
> > ahead and give their respective ethernet addresses against that IP
> > address (I have seen this with tcpdump). This causes the other machines to
> > pick up wrong ethernet address against the IP address.
> 
> Yep, this is the default behaviour since multiple links on one subnet is
> an unusual situation (I ran into the same problem).  The solution is to apply
> the arpfilter patch to the kernel, recompile, and then write a 1 to
> /proc/sys/net/ipv4/conf/all/arp_filter to enable it for all interfaces.
> This patch enforces that NICs will only respond to arps for IP addresses
> that they own.

The arp-filter patch is in the kernel since about 2.4.4, so you just need
to turn it on...

Ben

> 
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-- 
Ben Greear <greearb@candelatech.com>          <Ben_Greear@excite.com>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear