On September 1, 2005 at 23:05, Douglas Otis wrote:
--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 |
--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Actually the IETF has a practice of defining the MSB as bit 0. This
can be confusing when describing bit settings. Rather than
specifying the bit ordering, the settings were defined by value. A
bit with a value of 1 would be bit 15 per IETF big endian
conventions, and bit 0 per common little endian architectures. Bit
values of 1, 2, or 4 was an attempt to avoid this ambiguity.
I'm trying to write a technical summary of CSV, hence my initial
questions, especially on the details since I would like to include
example zone file record entries.
I want to confirm that bit value 1, 2, 3, ... in CSA terminology
corresponds to bit value 15, 14, 13, ... in RFC-1035 terminology.
If I have an SMTP client called smtp.example.com that I want
to authorize under CSA, I should have the following records in
my zone file:
_client._smtp.smtp.example.com. IN SRV 1 2 1 smtp.example.com.
smtp.example.com. IN A 172.30.10.33
If I want to inform SMTP servers that I provide CSA records for
all my clients, I'd have the following record in my zone file:
_client._smtp.example.com. IN SRV 1 3 1 _client._smtp.example.com.
I'm trying to understand the applicable uses of a Weight summed value
of 3. What are the cases where authorization is allowed, but target
must not be used for authentication? Is my use of Weight 3 in my
above assertion record appropriate?
If an SMTP server gets a Weight 3 on a client lookup, must it then do
an explicit address lookup to determine if the client is authenticated?
What is server behavior if a client is listed as authorized but
cannot be authenticated?
Thanks,
--ewh
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