[lug] sendto(2) problem with ipv4/ipv6 addresses...

Bear Giles bgiles at coyotesong.com
Mon Apr 2 13:08:10 MDT 2012

Dual network stack implementations can recognize IPv4 addresses within the
IPv6 address space.

It's unlikely but you could also try the older format ::aa.bb.cc.dd (drop
the :ffff:).


On Mon, Apr 2, 2012 at 11:55 AM, Zan Lynx <zlynx at acm.org> wrote:

> On Mon, 2012-04-02 at 12:38 -0600, Alan Robertson wrote:
> > As part of the Assimilation Monitoring project (assimmon.org), I've
> > been writing some UDP network code to send packets.  It seems to work
> > fine when sending to the ipv6 loopback address (::1), but not when
> > sending to ipv4 addresses.  I'm sending to ipv4 addresses by using the
> > ipv4 part of the ipv6 address space ("::ffff:aa.bb.cc.dd").  Tcpdump
> > is showing that nothing is being sent - so the kernel is blocking this
> > call before it goes out.
> I believe that using IPv4 addresses mapped in IPv6 requires a gateway
> device to convert the protocol from IPv6 to IPv4. This seems to be
> called NAT-PT.
> Here is one source I Googled that describes configuring it on Linux:
> http://tomicki.net/ipv6.router.php
> --
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