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Re: Despamming wholesale dialup

  • From: Derek Balling
  • Date: Mon Nov 02 15:05:20 1998

Yeah, but the SMTP will fail, then it will POP. The subsequent SMTP will go
through. 

Eudora (<4.1) also did that. Although Eudora 4.1+ now do parallel tasks, so
all bets are off on which one will hit and take effect first. :)

But this thread has severely degraded beyond the scope of NANOG. I think we
should take this one off-list.

D

At 05:58 PM 10/30/98 -0500, Dean Anderson wrote:
>Unless you use Microsoft products.  Outlook smtp's, then pops.
>
>		--Dean
>
>At 02:45 PM 10/30/98 -0800, Derek Balling wrote:
>>There are solutions available to this problem, the primary one being the
>>"smtp-after-pop" hack that is widely available and fairly widely used.
>>
>>Essentially, issuing a STAT command opens up an SMTP relay window for
>><admin-definable> minutes, whereupon if the user hasn't issued another STAT
>>in the mean time [e.g. they logged off] the "hole" goes away.
>>
>>We were using that at my last job and it works just fine.
>>
>>At 12:38 PM 10/30/98 -0600, Phil Howard wrote:
>>>Bryan Bradsby wrote:
>>>
>>>> Block port 25 (only) from all "open modem banks" (TM) to my SMTP servers. 
>>>> If implemented on a large enough scale, the modem user will be
>>>> 'encouraged' to use the SMTP server supplied with their account. Make each
>>>> dialup customer go through, and be authenticated by their own SMTP
>server. 
>>>
>>>I think I see an additional problem creeping in here.
>>>
>>>The question is whether a dialup user should use the SMTP server of the
>>>facility provider, or of the ISP that actually resells the account.  You
>>>could have virtual ISP resellers with no facilities at all, but lets take
>>>a look at a small ISP that does have facilities, and is reselling dialup
>>>to a national provider so his local business customers can have roaming
>>>access without calling an 800 number.
>>>
>>>If the small ISP opens their SMTP server to the IP addresses of the big
>>>national dialup provider, which they would have to do in order to be able
>>>to handle that roaming customer who could be just about anywhere, will
>>>they not also be opening themselves up to being a relay for any spammer
>>>that uses any reseller of that national provider?  Will not such spammers
>>>then have access to every ISP doing reselling via that national one?
>>>
>>>I think the SMTP server that should be used when dialing that national
>>>provider is the SMTP server provided by that national provider, unless
>>>some kind of VPN is used (to be more technically correct, use the SMTP
>>>server of the provider of IP addressing).
>>>
>>>Roeland's issue still applies when the dialup customer is using his domain
>>>name as the FROM/REPLY.  But if the national provider SMTP servers accept
>>>any domain name in the FROM/REPLY, and just log the reality as it sees it
>>>in the header (e.g. dialup port and time which can be cross checked with
>>>the access logs), then anyone can use these dialups, and spammers won't
>>>get an advantage of being able to spew their filth to other than the SMTP
>>>server of the dialup provider.
>>>
>>>-- 
>>> --    *-----------------------------*      Phil Howard KA9WGN       *    --
>>>  --   | Inturnet, Inc.              | Director of Internet Services |   --
>>>   --  | Business Internet Solutions |       eng at intur.net        |  --
>>>    -- *-----------------------------*      philh at intur.net       * --
>>
>>
>>
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