ISP port blocking practice

Suresh Ramasubramanian ops.lists at
Fri Sep 3 02:20:01 UTC 2010

BCP38 / RFC2827 were created specifically to address some quite
similar problems.  And googling either of those two strings on nanog
will get you a lot of griping and/or reasons as to why these aren't
being more widely adopted :)


On Fri, Sep 3, 2010 at 7:47 AM, Zhiyun Qian <zhiyunq at> wrote:
> Suresh, thanks for your interest. I see you've had a lot of experience in fighting spam, so you must have known this. Yes, I know this spamming technique has been around for a while. But it's surprising to see that the majority of the ISPs that we studied are still vulnerable to this attack.  That probably indicates that it is not as widely known as we would expect. So I thought it would be beneficial to raise the awareness of the problem.
> In terms of more results, the paper is the most detailed document we have. Otherwise, if you interested in the data that we collected (which ISPs or IP ranges are vulnerable to this attack). We can chat offline.
> Regards.
> -Zhiyun

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