Re: arp: SIOCSARP: No such device

really kuznet@ms2.inr.ac.ru (inr-linux-kernel@ms2.inr.ac.ru)
22 Jun 1996 20:15:36 +0400


Bernd Eckenfels (ecki@tapac.INka.DE) wrote:
: Bartlomiej Czardybon (czar@dumb.iinf.polsl.gliwice.pl) wrote:
: : o68:~/tmp# arp -s 157.158.29.94 00:C0:DF:49:9F:66
: : SIOCSARP: No such device

: This is because the kernel tries to guess the device you want to arp for. If
: you use not-published entries it looks for the device the route (for
: 157.158.29.94) points to and notices that this device isnt ARPabel.

He (kernel :-)) is right. You cannot setup an arp entry for not arpable
device. And if 157.158.29.94 is routed via not arpable device,
it is non-sence to setup arp entry for it, is not it?

: The
: Kernel would have guessed the first Ethernet Device if you have specified an
: published entry, which is most likely what u want to do:

: o68:~/tmp# arp -s 157.158.29.94 00:C0:DF:49:9F:66 pub

Correct explanation, but a bit wrong advice. If you really want to setup
proxy entry (it is not clear from Bartlomiej's mail, what he wanted really),
use:

arp -s 157.158.29.94 00:C0:DF:49:9F:66 dev eth0 pub

: PS: Yes the device guessing needs some improvement...

Device guessing for proxy entries works when
you have only one arpable interface. If you have more than one such
interface, kernel cannot read your thoughts :-), so that
you must specify device explicitly.

Alexey Kuznetsov.