netdev - Re: [PATCH iproute2] ip-address: properly display zero IPv4 peer address

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 11 Nov 2015 12:34:02 +0100
From:	Phil Sutter <phil@....cc>
To:	Thomas Haller <thaller@...hat.com>
Cc:	netdev@...r.kernel.org,
	Stephen Hemminger <stephen@...workplumber.org>
Subject: Re: [PATCH iproute2] ip-address: properly display zero IPv4 peer
 address

On Thu, Oct 22, 2015 at 10:34:28AM +0200, Thomas Haller wrote:
> Kernel allows for zero IPv4 peer addresses (IFA_ADDRESS):
> 
>    ip address add 192.168.5.1 peer 0.0.0.0/24 dev dummy
> 
> which is distinct from a usual address like:
> 
>    ip address add 192.168.5.1/24 dev dummy
>    ip address add 192.168.5.1 peer 192.168.5.1/24 dev dummy
> 
> For IPv4, a missing IFA_ADDRESS attribute means that the peer
> is 0.0.0.0. See inet_fill_ifaddr(), which does:
> 
>   if ((ifa->ifa_address &&
>        nla_put_in_addr(skb, IFA_ADDRESS, ifa->ifa_address)) ||
> 
> Signed-off-by: Thomas Haller <thaller@...hat.com>

Acked-by: Phil Sutter <phil@....cc>

I wonder why this is not the case for IPv6. What is the functional
effect of setting a zero peer with non-zero netmask?

Cheers, Phil
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html