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From: Brian Haley <brian.haley@hp.com>
To: charles@kde.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	netdev@vger.kernel.org, bugzilla-daemon@bugzilla.kernel.org,
	bugme-daemon@bugzilla.kernel.org
Subject: Re: [Bugme-new] [Bug 15720] New: IPv6's ipv4-compatibility addresses don't bind
Date: Tue, 13 Apr 2010 11:06:38 -0400	[thread overview]
Message-ID: <4BC4887E.1050801@hp.com> (raw)
In-Reply-To: <20100412212241.d8bf4185.akpm@linux-foundation.org>

Andrew Morton wrote:
>> When attempting to bind to an address using ipv4-compatibility, for example,
>> "::ffff:127.0.0.1", Linux refuses to bind to that address when
>> /proc/sys/net/ipv6/bindv6only is set.

This is actually not a (deprecated) IPv4-compatible IPv6 address (::127.0.0.1),
but an IPv4-mapped IPv6 address.

>> It seems to me that the intent of "bindv6only" was to not bind to the ipv4
>> address when you bind to all addresses (specifically ipv6 address "::"). So
>> when you bind to ::, an ipv4 client connects to you, and it appears to be
>> connecting from ::ffff:192.168.5.5. I don't think its intent was to effectively
>> disable binding to ::ffff:x.x.x.x addresses - just breaking that feature makes
>> no sense.

It is documented in ip-sysctl.txt:

bindv6only - BOOLEAN
        Default value for IPV6_V6ONLY socket option,
        which restricts use of the IPv6 socket to IPv6 communication
        only.
                TRUE: disable IPv4-mapped address feature
                FALSE: enable IPv4-mapped address feature

        Default: FALSE (as specified in RFC2553bis)

-Brian

      reply	other threads:[~2010-04-13 15:06 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-15720-10286@https.bugzilla.kernel.org/>
2010-04-13  1:22 ` [Bugme-new] [Bug 15720] New: IPv6's ipv4-compatibility addresses don't bind Andrew Morton
2010-04-13 15:06   ` Brian Haley [this message]

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