netdev - Re: [PATCH net-next] net: bridge: do not send arp replies if src and target hw addr is the same

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Message-ID: <6b43ec63a2bbb91e78f7ea7954f6d5148a33df00.camel@redhat.com>
Date: Tue, 09 Jan 2024 12:36:06 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Felix Fietkau <nbd@....name>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: bridge: do not send arp replies if src
 and target hw addr is the same

On Thu, 2024-01-04 at 15:25 +0100, Felix Fietkau wrote:
> There are broken devices in the wild that handle duplicate IP address
> detection by sending out ARP requests for the IP that they received from a
> DHCP server and refuse the address if they get a reply.
> When proxyarp is enabled, they would go into a loop of requesting an address
> and then NAKing it again.

Can you instead provide the same functionality with some nft/tc
ingress/ebpf filter?

I feel uneasy to hard code this kind of policy, even if it looks
sensible. I suspect it could break some other currently working weird
device behavior.

Otherwise it could be nice provide some arpfilter flag to
enable/disable this kind filtering.

Cheers,

Paolo