Stealth Blocking

Roeland Meyer rmeyer at mhsc.com
Fri May 25 00:49:54 UTC 2001



> From: Mitch Halmu [mailto:mitch at netside.net]
> Sent: Thursday, May 24, 2001 2:48 PM
> 
> On Thu, 24 May 2001, Matt Cramer wrote:

> I will give you a solid reason why we won't try this, quoting 
> research 
> with POP-before-SMTP conducted by the founder of MAPS TSI, 
> Chip Rosenthal 
> http://users.laserlink.net/~chip/relay-pres-9910/
> 
> You don't have to believe me that our clients will not accept 
> that, take
> his words instead:
> 
> "Our users hated it - particularly those using MS Outlook"
> 
> No need to describe what happens when your clients hate your 
> service...

On that same page, I found this very interesting. The part about false
positive, to normal relay testing, got my attention.

Guys, there are more cases that may look like an open relay, but really
aren't.

<quote>
Escalating Credentials
Curently deployed in Laser Link network

Amalgamation of two mechanisms:

POP-before-SMTP

Rate limiting

Count mail from originating IP address

...

Disadvantages:

Complex implementation

Will users accept upper limit?

False positive to conventional relay testing
</quote>






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