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Re: [Asrg] For DNSBLs, embedded IPv4 in IPv6

2008-08-04 03:43:53
Tim Chown wrote:
 
An excellent reference for application developers is RFC4038.

Thanks for the pointer.  This might be overkill for the rather
simple goals of a DNSBL with IPv6 addresses, but a reference to
RFC 3901 (mentioned in RFC 4038) can be added to the DNSBL I-D.

Looking for some 'test' address where currently 127.0.0.2 is
used for the IPv4-only application?   What is the purpose of 
the test address?

The test address tells you that a DNSBL is alive and kicking.

If "name" 2.0.0.127.dnsbl.example. has an 127/8 "address", then
IP 127.0.0.2 is listed.  In theory this one "test string" can
be used for any DNSBL (IPv4, IPv6, both, more) and even RHSBL.

In practice some RHSBLs use something else, e.g., example.tld.
They have a 127/8 "address" for say example.tld.rhsbl.example.

It would be nice to have test entries for each type of list,
it makes no sense to bother pure RHSBLs with IP queries, etc.

Similar lists have test address that is *never* listed, that
allows to catch stupid errors (or stupid exit strategies of
list operators trying to shut down their service).

127.0.0.1 is never listed.  It is intuitive to extend this to
::1 and localhost.  How to extend the always listed 127.0.0.2
is less obvious, ::2 is the idea in the draft at the moment,
and IIRC "test" for RHSBLs.  In the meeting somebody proposed
to use "test.invalid" or only "invalid" instead of "test".

All okay, no last minute changes to the 2606bis I-D required.
But IPv6 is less clear, I proposed ::FFFF:127.0.0.2

You are apparently saying that this is *too* intuitive:  We
expect clients to use the (reverse) IPv4 presentation form
for all mapped addresses, and therefore an exception is not
KISS enough.  So maybe ::2 is fine, or I will learn whatever
IPv6 example address is used as test address, no big deal...

 Frank

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