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

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Date:	Tue, 17 Mar 2009 01:18:09 +0100
From:	Felix von Leitner <felix-kernel@...e.de>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	netdev@...r.kernel.org
Subject: Re: socket api problem: can't bind an ipv6 socket to ::ffff:0.0.0.0

> > 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.

No I don't have anything else on that port.

BTW, just for the record, binding to ::ffff:10.0.0.3 (my eth0 address at
the moment) still works, so the mechanism is not completely broken.

Felix
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