Re: arp: SIOCSARP: No such device

Bernd Eckenfels (
2 Jul 1996 19:22:03 GMT

really ( wrote:
: : arp -i eth0 -D -s eth0 pub
: ^ ^
: Is it misprint? Why twice?
Because the first option (dev eth0) will fill the device field and the
arguemtn (-D eth0) will fill the hardware-address). I dont wanted to asume
that the user intends it, I can think of:

arp -e eth0 -D -s eth1 pub

in a situation where u have 2 network cards connected for fallback securtiy.
What I'm going to do will be:

arp -s dev eth0 pub (==arp -i eth0 -s pub) will set the
entry for eth0 with the address of eth0.
: : arp -s xx:xx:Xx:xx:xx:xx pub
: : should work.
: It worked in 1.2 if you had one arpable interface. And it still works.
: We cannot make this thing backward compatible because
: old arp COULD NOT handle proxies for multiple arpable devices.

Thats not quitew correct. It could handle the situation of 2 ethernt cards
automatically, since it refused to answer requests on the routed device.
Therefore a lot of hosts with 2 interfaces (which is the most common case
anyway) will not work anymore. I dont think we should 'stretch' linux users
too far away from normal arp-syntax.

: This command published on all arpable interfaces,

except the one interface the net was attached to, which will work fine with
2 nic.

: that was apparently wrong (two ethernets cannot have coincident adresses).

: New arp is FULLY compatible with old, when you have just one arpable
: interface, and it adds new functionality.

: : even if that looks very odd.
: Well, it would not look very odd if you omitted redundant device
: specification :-).

As I said before its not redundant, removing one of them will force arp to
guess about the users intention. But I will work around this with the above
solution, this syntx may remain valid.

: It is one of the places, where old functionality should be dropped as soon
: as possible. ARP and proxy ARP are absolutely different things,
: BSD made mess from them and we will have to teach people, that one
: command cannot delete both apples and boxes for oranges :-)

Well, but it used to do that :)


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