nanog mailing list archives

Re: Outgoing SMTP Servers


From: Jack Bates <jbates () brightok net>
Date: Mon, 31 Oct 2011 22:46:24 -0500

On 10/31/2011 8:12 PM, Brian Johnson wrote:

Sent from my iPad

On Oct 31, 2011, at 1:30 PM, "Jack Bates"<jbates () brightok net>  wrote:


On 10/31/2011 11:48 AM, Michael Thomas wrote:
I've often wondered the same thing as to what the resistance is to outbound
filtering is. I can think of a few possibilities:

1) cost of filtering
2) false positives
3) really _not_ wanting to know about abuse
On the other hand, you have

1) cost of tracking
2) support costs handling infections

It's really an range from "easiest and cost effective" to "doing it right". I personally run hybrid. There are areas that are near 
impossible to track; this is especially true for wide area wireless/cellular/NAT areas. I always recommend my customers block tcp/25, even to the local 
smarthosts. Use 587 and authentication to support better tracking. It's a hack, though, as it doesn't stop other abuses and it won't fix the 
underlying root cause.
Let me know when u can "fix" the root causes. The two I know of:
1. Bad actors
2. Clueless users

While true, from a security viewpoint, the root cause is loss of control over the system involved. Spam, while perhaps the most visible and annoying to others is not my highest concern (We find the number of clueless users direct spamming is miniscule compared to hijacked systems). My concern is that the customer has lost control of their machine and could at that moment be unknowingly giving out critical information.

-Jack


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