ipv4_devconf.arp_accept mystery

ipv4_devconf.arp_accept mystery

[Ian Brown]

Hello,
I have a question regarding unsolicited ARPs in ipv4/arp.c

As I understand, by default this feature is disabled;
How can one set this feature ?

When working with ipv4_devconf.arp_accept is 0 by default.
This is with 2.6.21 kernel.

I wanted ipv4_devconf.arp_accept to be set to 1.

I added:
net.ipv4.conf.default.arp_accept = 1
net.ipv4.conf.eth0.arp_accept = 1
in /etc/sysctl.conf
and rebooted.

I have:
cat /proc/sys/net/ipv4/conf/default/arp_accept
=> 1
cat /proc/sys/net/ipv4/conf/eth0/arp_accept
=>1

Yet ,the printk() I added shows that ipv4_devconf.arp_accept shows 0 !!


Could it be that this variable could not be set ? or is it dependent
upon other things ?

BTW, in newer kernel version we have IPV4_DEVCONF_ALL(ARP_ACCEPT)
instead. So if anybody knows how to set this macro (instead)to be 1, it will be
also fine.


Ian

Re: ipv4_devconf.arp_accept mystery

[Herbert Xu]

Ian Brown <ianbrn@gmail.com> wrote:
>
> BTW, in newer kernel version we have IPV4_DEVCONF_ALL(ARP_ACCEPT)
> instead. So if anybody knows how to set this macro (instead)to be 1, it will be
> also fine.

As the name suggests you should use

	/proc/sys/net/ipv4/conf/all/arp_accept

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: ipv4_devconf.arp_accept mystery

[Ian Brown]

Hello,

>As the name suggests you should use
>     /proc/sys/net/ipv4/conf/all/arp_accept
 Thanks. This is indeed true.
I first tried with ipv4_devconf.arp_accept, where the name probably
does **not** suggest it; I agree
that  for PV4_DEVCONF_ALL() the name indeed suggests it . It just
skipped my eye. I suppose this is true also to
ipv4_devconf.arp_accept.

Rgs,
Ian



On Dec 24, 2007 2:51 PM, Herbert Xu <herbert@gondor.apana.org.au> wrote:
> Ian Brown <ianbrn@gmail.com> wrote:
> >
> > BTW, in newer kernel version we have IPV4_DEVCONF_ALL(ARP_ACCEPT)
> > instead. So if anybody knows how to set this macro (instead)to be 1, it will be
> > also fine.
>
> As the name suggests you should use
>
>         /proc/sys/net/ipv4/conf/all/arp_accept
>
> Cheers,
> --
> Visit Openswan at http://www.openswan.org/
> Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
>

Re: ipv4_devconf.arp_accept mystery

[Benny Amorsen]

Herbert Xu <herbert@gondor.apana.org.au> writes:

> As the name suggests you should use
>
> 	/proc/sys/net/ipv4/conf/all/arp_accept

The documentation says that if arp_accept is 0, unsolicited arp
replies are dropped. Doesn't that interfere with failover services
such as vrrp, keepalived, ucarp etc? I thought they did unsolicited
arp when failing over.


/Benny