[PATCH 3/7 net-2.6.25] [IPV4]: Prohibit assignment of 0.0.0.0 as interface address.

[Daniel Lezcano]

Denis V. Lunev wrote:
> Daniel Lezcano wrote:
>> Denis V. Lunev wrote:
>>> I could hardly imagine why sombady needs to assign 0.0.0.0 as an
>>> interface
>>> address or interface destination address. The kernel will behave in a
>>> strage
>>> way in several places if this is possible, as ifa_local != 0 is
>>> considered
>>> as initialized/non-initialized state of the ifa.
>> AFAICS, we should be able to set at an interface address to 0.0.0.0, in
>> order to remove an IP address from an interface and keep this one up.
>> I see two trivial cases:
>>  * remove the ipv4 on an interface but continue to use it through ipv6
>>  * move ipv4 address from the interface to an attached bridge
> 
> For this case there is an IOCTL/netlink "remove IP address".

And I forgot to mention the general broadcast.
This is need for the dhcp protocol. If you are not able to set your 
interface to 0.0.0.0, you will be not able to send a 255.255.255.255 
broadcast message to have your IP address.