netdev - Re: socket api problem: can't bind an ipv6 socket to ::ffff:0.0.0.0

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Date:	Mon, 16 Mar 2009 17:00:40 -0700
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Felix von Leitner <felix-kernel@...e.de>
Cc:	netdev@...r.kernel.org
Subject: Re: socket api problem: can't bind an ipv6 socket to ::ffff:0.0.0.0

On Tue, 17 Mar 2009 00:48:10 +0100
Felix von Leitner <felix-kernel@...e.de> wrote:

> Here's an strace:
> 
> socket(PF_INET6, SOCK_STREAM, IPPROTO_IP) = 3
> fcntl(3, F_GETFL)                       = 0x2 (flags O_RDWR)
> fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK)    = 0
> setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
> bind(3, {sa_family=AF_INET6, sin6_port=htons(6969), inet_pton(AF_INET6, "::ffff:0.0.0.0", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = -1 EADDRNOTAVAIL (Cannot assign requested address)
> 
> This is supposed to work, and it works on other operating systems, even
> on Mac OS X.
> 
> I think it used to work on Linux, too.
> 
> I'm using 2.6.29-rc7 right now, but others have reported this not
> working on distro kernels, too.
> 
> Felix
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Most likely you already have same port open on IPV4 and unless
you set IPV6 only, the bind bind will fail. The standard way
of doing servers is to bind only for IPV6 and handle IPV4
clients via the 6-4 address mapping.
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