[PLUG] ARP black magic question

[Zot O'Connor]

On Tue, 2003-08-26 at 18:45, Eric Harrison wrote:
> On Tue, 26 Aug 2003, Galen Seitz wrote:
> 
> >Eric Harrison <eharrison at mail.mesd.k12.or.us> wrote:
> >
> >> >> That is, when some random host sends out an arp query "who has serverb?",
> >> >> Server A needs to respond "serverb is at 01:02:03:04:05:06", where 
> >> >> "01:02:03:04:05:06" is the real MAC address for server B. 
> >> 
> >> >The question is, do you want to proxy an IP or a mac address?
> >> 
> >> I'm not trying to _proxy_ arp. The kernel doc's say that proxy_arp
> >> forwards arp packets between two devices attached to different media.

> Let it surfice to say that if "serverB" crashes, or is otherwise
> unavailable, things will still work perfectly as long as the other
> servers/routers/etc on the same physical network *think* "serverB"
> is still up.



I should not have said the word proxy, but what I wrote should work just
fine.

ServerA will publish an arp for server B.  All responses will goto A. 
What I failed to mention above is my serverA knew what to do with the
packet (forward it to the network) because of routing rules.

If you are merely usurping B's mac then
  arp -i eth0 -s hostname hw_addr [netmask nm] pub

where hostname is B's IP address, and hw_addr is B's MAC, eth0 is the
appropriate interface.  Netmask is optional

I believe you need the IP and hw_addr.

-- 
Zot O'Connor

http://www.ZotConsulting.com
http://www.WhiteKnightHackers.com