ISP port blocking practice

Sat Oct 24 02:35:31 UTC 2009

On 23/10/09 17:43 -0500, Justin Shore wrote:
>> It does block incoming SMTP traffic on that well known port.
>
> Then the customer should have bought a class of service that permits  
> servers.

That justification is a slippery slope. At what point do you draw the line
on what constitutes business use? Is running a web server business use? A
mail server? What about a server which participates in a peer to peer
network? VPN?

I certainly think you're within your right as a network operator to
determine what is business use. I don't happen to feel that running a
protocol server in and of itself meets that definition.

>> Would you consider restricting a customer's outgoing port 25 traffic to a
>> specific mail server a step over the net neutrality line?
>
> I do this all the time.  For example I don't let my customers send or  
> receive mail (or any traffic for that matter) from prefixes originating  
> from AS32311 (Colorado spammer Scott Richter).  Now if I was blocking  
> mail to dnc.org, gop.com, greenpeace.org, etc or restricting Vonage to  
> .05% of my bandwidth then yeah that would violate net neutrality  
> principles.  The difference is one stifles speech and is  
> anti-competitive.  The other mitigates a network security and stability  
> risk.

I think I worded my question a bit wrong. I meant to hypothetically propose
a common scenario: You only allow your customers to connect to your SMTP
server, and if they attempt to connect to *any* other SMTP server, they are
blocked or redirected to your SMTP server.

-- 
Dan White