On Mar 9, 2007, at 10:17 PM, David Morris wrote:
In the low end bandwidth space I play, a extra 192 bits on every
packet is significant to end user performance. As others have
noted, it seems like the fairly effective anti-spam technique of
associating reputations with network addresses will be stressed by
exploding the number of addresses ... stressed because the
originators of spam will be able to be more agile and because the
memory and CPU required to track such reputations explodes.
Perhaps by the time IPV4 scarcity is a critical economic issue, the
continuing trend of cheaper faster last mile internet connectivity
as well as server system capability cost reductions will
converge... or perhaps some combination of legal and techical
solutions will push spam into the noise level. Etc.
Unwanted traffic will likely become much worse. DKIM is an example
of how it took years to define a domain-specific cryptographic
signature for email. Although defining a signing policy remains, it
is doubtful the results will prove practical at controlling
cryptographic replay abuse in a diverse network landscape. Where a
responsible signer might rate-limit account holders or exclude bad
actors, some means is still needed to authorize transmitters to
determine whether an assumption of control is still valid. DKIM has
no safe provision to authorize transmitters unless within the domain
of the signer. It seem unreasonable, when considering how diverse a
IPv4/IPv6 landscape will become, to then expect all related network
providers will obtain a zone from each of their customer's domains
and configure it for each of the protocols. That constraint
represents an administrative nightmare.
DKIM can be adjusted, but can this be done within a suitable
timeframe? Without a name-to-name authorization scheme, controlling
abuse will remain by the IP address. When those addresses happen to
be gateways into IPv4 space operating as giant NATs, the collateral
impacts will make today's problems seem like the good old days.
Retaining an open system of communication may then become untenable,
and that would be a shame.
-Doug
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