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== HacDC's MX record broken, can't send mail to lists ==


Dangit. I'm sure someone will find this here, as I'm unable to send to any of the mailing lists. Here's a convo between me and my admin:
12:39 <myself> hey, I keep getting this whenever I try to send to hacdc: <br/>
12:39 <myself>  blabber@hacdc.org <br/>
12:39 <myself>'''    all relevant MX records point to non-existent hosts or (invalidly) to IP addresses '''<br/>
12:40 <myself> but there's plenty of traffic on the list, others obviously have no problems <br/>
12:40 <myself> I mentioned it to one of them through his personal email, and didn't hear back. Is this something you can look into? <br/>
13:03 <paul> paul@ptimmins-d:~$ host hacdc.org <br/>
13:03 <paul> hacdc.org has address 208.72.84.15 <br/>
13:03 <paul> '''hacdc.org mail is handled by 0 69.89.31.218. '''<br/>
13:03 <paul> that's invalid <br/>
13:03 <paul> cant' fix <br/>
13:04 <paul> '''mx records have to point to names per rfc''' <br/>
13:05 <myself> ahh, okay <br/>
13:05 <myself> thanks <br/>
13:05 <paul> that should be something like <br/>
13:05 <paul> MX 0 mail.hacdc.org. <br/>
13:05 <paul> with mail.hacdc.org. IN A 69.89.31.218 <br/>
13:06 <myself> and everyone else's MTAs just silently accept the misconfiguration and do the right thing anyway <br/>
13:07 <paul> where by "the right thing" you mean "do what I mean not what I say" <br/>
13:07 <paul> yes <br/>
13:08 <paul> they added extra code paths to compensate for the dns calls not returning shit they should <br/>
13:08 <paul> when you pull an A record, the IPs get returned in binary <br/>
13:08 <paul> when you pull an MX record, it spells out the data in ascii because it's supposed to be another name <br/>
13:09 <paul> which you can then do a gethostbyname() on and get an ip <br/>
13:10 <paul> so other MTAs have an entire codepath where they try to parse an ASCII string of an IP address to stuff it into a connect() <br/>
13:10 <paul> which is as bad of an idea as it sounds, securitywise <br/>
Fixed - thanks for the heads up!

Revision as of 17:39, 30 April 2009