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SubjectRe: how to see manually specified proxy arp entries using "ip neigh"
"Matthew G. Marsh" wrote:

> > Currently I have been doing this by manually setting proxy arping on the NIC for
> > the IP address assigned to the ethertap device. If this feature is going to be
> > removed, then how should I be doing this?
> If an IP address is routed to on the external network then it will be
> available. It does _not_ matter what interface that address is assigned
> to. EX:
> ip addr add dev dummy0
> ip link set dev dummy0 up
> now ping from another machine on eth0 that has an appropriate
> route. I suspect what is really biting you is that your rp_filters are way
> too restrictive on your machine.

Sorry, I guess I explained it wrong. Ethertap has an IP address assigned to the
device in the linux kernel. It is then configured with a point to point route
to another IP address on the other concepual end of the link (ie in userspace).
It is this other IP address that I am proxy arping for.


[mtc@ mtc]$ /sbin/ip add
<stuff removed>
4: tap0: <BROADCAST,MULTICAST,NOARP,UP> mtu 1500 qdisc noqueue
link/ether fe:fd:00:00:00:00 brd ff:ff:ff:ff:ff:ff
inet peer brd scope global tap0

[mtc@ mtc]$ /sbin/ip ro dev tap0 proto kernel scope link src
<stuff removed>

[mtc@ mtc]$ /sbin/arp
Address HWtype HWaddress Flags Mask Iface
<stuff removed * * MP eth1

Thus, anyone arping for (which is on top of a protocol stack in
userspace) will get the MAC address of eth1 as a response.

I cannot turn on proxy arping for the interface in general as I have eth0 and
eth1 on the same subnet and turning on proxy arping causes bad things to
happen. Thus I have a single manual proxy entry in the arp table.

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:
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