nanog mailing list archives
Re: dnsbl's? - an informal survey
From: "Crist J. Clark" <crist.clark () attbi com>
Date: Fri, 30 May 2003 10:59:50 -0700
Oh, the irony of this thread being initiated by someone with an @covad.com address. ;) I don't have an answer for the originator, but this reminded me of something about DNSBLs that I've been meaning to ask. Does anyone know of a black hole list of dynamic cable and DSL clients? What I really want is one that mimics AOLs block list of dynamic IPs. I HUGE portion of the spam we were (and still are) receiving came out of attbi.com, swbell.com, pacbell.com, covad.com, etc. DSL and cable customers, and almost no legitimate mail. Manangement resisted blocking those IPs until AOL lead the way. "If they can't send to AOL either, they can't complain that we're being unreasonable. They'll have to break down and fix their mail servers." However, trying to figure out which blocks of IPs these ISPs use for dynamic connections (which we want to block) versus static allocations (which we may not wish to) is non-trival. The few "dynamic" DNSBLs I've found haven't provided enough documentation about what they actually are trying to include. Plus, when I tested them, they didn't seem to block some of the most obvious culprits. (Before anyone starts arguing the merits of blocking dynamic addresses, you might as well try to tell me why you need to run an open relay and I shouldn't block it. I have a dynamic address at home, and I am blocked by my own filters at work. I figured out long ago that my home MTA needs to route outgoing email via my ISP's outgoing SMTP servers, and it has never caused me any problems.) -- Crist J. Clark | cjclark () alum mit edu | cjclark () jhu edu http://people.freebsd.org/~cjc/ | cjc () freebsd org
Current thread:
- dnsbl's? - an informal survey Williamson, Todd (May 29)
- Re: dnsbl's? - an informal survey listuser (May 29)
- <Possible follow-ups>
- Re: dnsbl's? - an informal survey Crist J. Clark (May 30)
- Re: dnsbl's? - an informal survey Andy Smith (May 30)
- Re: dnsbl's? - an informal survey Jack Bates (May 30)
- Re: dnsbl's? - an informal survey listuser (May 30)
- Re: dnsbl's? - an informal survey Charles Sprickman (May 30)
- Re: dnsbl's? - an informal survey Mr. James W. Laferriere (May 30)
- Re: dnsbl's? - an informal survey Jack Bates (May 30)
- Re: dnsbl's? - an informal survey Mr. James W. Laferriere (May 30)
- Re: dnsbl's? - an informal survey Jack Bates (May 30)
- Re: dnsbl's? - an informal survey Mr. James W. Laferriere (May 31)
- Re: dnsbl's? - an informal survey jlewis (May 31)
- Re: dnsbl's? - an informal survey Andy Smith (May 30)