Incorrect ARP response (network)

Sanjuro sanjuroe at
Sat Nov 30 10:41:07 PST 2002

 > it suggested the use of rp_filter and arp_filter,
 > so I don't even have to apply the patch.

Correction. It appeared to work, but it doesn't. Setting arp_filter to 1 
does only send 1 ARP reply, but always with the MAC address of eth0.

So I guess I will have to apply the patch. BUT on my system it doesn't 
apply cleanly to kernel 2.4.20.

Could someone please confirm that it doesn't? I almost bothered a kernel 
driver maintainer with something simple, don't want to bother anyone 
else unnecessarily.


Sanjuro wrote:
>  > You're not going to like hearing this, but that's the default
>  > behaviour for the 2.4.x kernels
> You're right, from my point of view this is a very strange default 
> behaviour. But according to the Linux kernel doc this behaviour 
> "increases the chance of successful communication". Although I can't 
> think of a situation in which this would apply.
>  > Don't do that.  They might also point and laugh at you.  ;)
> Yes, well I thought they might if I had reported it. But I have spend 
> days trying to track down the problem, and i DID use Google. But I 
> couldn't find anything to help me. Now I know what the problem is I know 
> what to search for and now I found some usefull information, but still 
> some things are unclear. But how could I have found this on my own?!? 
> (This doesn't mean that I don't appreciate your help, i do, very much so.)
>  > with 2.4.x you do need a patch to change this behaviour
>  > Don't forget to read the little hidden.txt file
> That was very helpfull, it suggested the use of rp_filter and arp_filter 
> for my setup (2 NICs on 1 hub), so I don't even have to apply the patch. 
> I did and everything is working know as -I- expect it too.
> But I fully agree with some other people who posted to other 
> mailinglists (I found them with Google once I knew what to look for) who 
> complained about lack of documentation about this subject.
> Thank you for this reply,
> Sanjuro

Unsubscribe: send email to listar at
and put 'unsubscribe blfs-support' in the subject header of the message

More information about the blfs-support mailing list