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Re: [Asrg] Another dnsbl draft, now standards flavored

2008-07-29 10:32:49

On Jul 29, 2008, at 10:26 AM, Chris Lewis wrote:

Tony Hansen wrote:
My take:
Think of DNSxL as an exercise in steganography: A few bits of information are encoded into something that looks an awful lot like an IP address and can be carried over a channel intended to transmit IP addresses. Otherwise it's an opaque value. The choice of 127.0.0.0/8 and ANY sort of range in the IPv6 address space is truly irrelevant. These are not IP addresses; they just look like IP addresses.

Correct. But having the DNSBL return addresses that may actually be in use means that you can't tell the difference between a correctly operating DNSBL and an ordinary DNS server returning real IP addresses.

Eg: a DNSBL domain gets typo-squattered (or reclaimed), whereupon the domain owner puts in wildcarded A records pointing at their click thru advertising page. In ipv4 space, there is a not insignificant fraction of DNSBL clients that will treat this as meaning all IPs are listed. The slightly better ones know that non-127/8 returns should be ignored.

We need the same safety net in ipv6.

You'd only need the same safety net for IPv6 responses if you decided to have a DNSBL return IPv6 responses, which I don't think anyone is seriously suggesting, are they?

Otherwise, it returns an A record and, after you've gone through the step of converting the IP address you're querying to a hostname, everything behaves identically for v4 and v6 queries.

Cheers,
  Steve

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