[ntp:questions] ipv6 support on linux - bind problem

Wolfgang S. Rupprecht wolfgang.rupprecht+gnus200704 at gmail.com
Sat Apr 7 18:14:04 UTC 2007

mayer at ntp.isc.org (Danny Mayer) writes:
> This definitely shows a problem. Either there is something else running
> and binding to the wildcard IPv6 socket or there is a problem with
> support of IPv6.

I've seen this problem with other programs under linux's ipv6.  The
problem is that the linux stack unlike the Kame stack used in BSD's
uses mapped ipv4 addresses in ipv6.  If one opens up a whildcard
listening socket for both the ipv4 stack (with AF_INET) and then again
for the ipv6 stack (with AF_INET6), one ends up trying to open the v4
port a second time through the mapped-address.  The trick is to only
open up the AF_INET6 socket - it implies the ipv4 mapping.

I imagine this effects any daemon listening on an ipv6 socket in

Wolfgang S. Rupprecht                http://www.wsrcc.com/wolfgang/

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