On Tue, 25 Jul 2000, Jim Bound wrote:
> >> An af_inet6 socket should not accept a connection for an af_inet socket.
> >
> >you are right. they should open another af_inet socket and fall back to
> >an ipv4 connection. however, rfc2553 does not even suggest this behaviour.
> >quoting from draft-ietf-ipngwg-rfc2553bis-00.txt, section 3.7:
>
> OK I explained this in mail last night my "for" statement implied to much
> for any reader. Assume you have that mail?
yes, certainly.
> >let me understand, when an af_inet6 socket opens a connection with
> >another af_inet6 socket with ipv4-mapped address, the communication
> >established is in ipv4, isn't it? so ipv4-mapped addresses are not only
> >used for node representation (as they are returned from getaddrinfo and
> >getipnodebyname), but also to establish a connection to an ipv4 host.
>
> This is permissible but not required. The API can ask for just plain
> old IPv4 addresses too using af_inet with the API. How thats
> implemented in the stack is none of the standards groups business.
however, rfc2553 states that an application can use ipv4-mapped addresses
to open a TCP connection or send a UDP datagram to an ipv4 node. how can
this happen if the connection is not in ipv4?
> >so the only protocol that requires ipv4-mapped addresses "on the wire"
> >is SIIT. if SIIT is not used, then the kernel can reject all connection
> >from outside with an ipv4-mapped address, for security issues - like
> >itojun has explained us very well.
>
> This should be permissable and I think we need to add a socket level
> option for af_inet6 that states do not accept v4mapped connections, for
> af_inet6 listeners.
>
> This would be reflected in the next iteration (hopefully last call)
> in rfc2553bis.
imho such a sockopt is surely a good idea.
> >by the way, can you point me to a rfc which explains the difference
> >between a hybrid stack and a dual stack?
> Hmmm.
thank you very much for your answer.
--
Aequam memento rebus in arduis servare mentem...
Mauro Tortonesi [EMAIL PROTECTED]
Ferrara Linux User Group http://www.ferrara.linux.it
Project6 - IPv6 for Linux http://project6.ferrara.linux.it
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