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Re: SPF @ AOL --- record may flicker

2004-01-12 17:51:58
I wonder if AOL would be interested in tracking the failures via logging incoming DNS requests. They could probably set up a DNS server or two with logging turned on for this purpose.

Granted, most of these will be attempts to forge @aol.com in spam, but if there are a large number from any given client they can use that info to find something they may have missed.

In case this is helpful, I'm attaching a recipe showing how I did this at my site...



example SPF record:  (our assumes everything is forged)
altavista.com. IN TXT "v=spf1 +exists:CL.%{i}.FR.%{s}.HE.%{h}.null.spf.altavista.com -all"

Possible use for aol
aol.com. IN TXT "v=spf1 ip4:152.163.225.0/24 (etc, etc) ptr:mx.aol.com +exists:CL.%{i}.FR.%{s}.HE.%{h}.null.spf.aol.com ?all"

Incoming queries can be sent to a special server with logging on by giving the subdomain its own NS records:
spf.aol.com.   IN    NS    ns-logger.xy.aol.com.

I loaded mine with a small zone, since we just want to log the queries, they will all return "unknown host name" (NXDOMAIN).
$ORIGIN spf.altavista.com.
$TTL 7200
@       IN      SOA     ns-admin.sv.av.com. postmaster.av.com. (
       2003121500      ; serial
       3600            ; refresh
       900             ; retry
       604800          ; expire
7200 ) ; minimum@ IN NS ns-admin.sv.av.com.

@               IN      TXT             "v=spf1 -all"
@ IN TXT "No legit email comes from spf.altavista.com."


I use the following with BIND at the top of named.conf to log queries:
logging {
      category default { default_syslog; default_debug; };
      category panic { default_syslog; default_stderr; };
      category packet { default_debug; };
      category eventlib { default_debug; };
      channel query_channel {
              file "/var/adm/named.queries" versions 3 size 500m;
              print-time yes;
              print-category yes;
      };
      category queries {
              query_channel ;
      };
};

Once this is done the queries look like this:
12-Jan-2004 16:34:31.668 queries: XX /206.168.119.106/CL(_dot_)24(_dot_)162(_dot_)54(_dot_)27(_dot_)FR(_dot_)prknrzmmup_65952\(_at_)altavista(_dot_)com(_dot_)HE(_dot_)cs24
16254-27.houston.rr.com.null.spf.altavista.com/A/IN

The text of the query shows the following info:
/ip/ - server sending us the query (usually a DNS server near the mail receiver)
 CL.ip - Client IP address which presented the aol.com mail
 FR.*  - FROM address claimed in the mail envelope
 HE.*  - HELO address of the server - usually fake, sometimes missing


Hope this helps...

--
Greg Connor <gconnor(_at_)nekodojo(_dot_)org>

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