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Re: What do you want your ISP to block today?
On zaterdag, aug 30, 2003, at 18:54 Europe/Amsterdam, Owen DeLong wrote:
Christopher L. Morrow's mention of asymmetric routing for multihomed customers is more to the point, but if we can solve this for all those single homed dial, cable and ADSL end-users and not for multihomed networks, I'll be very happy.
I'm sure knife salespeople find it extremely annoying that they can't bring their wares along as carry-on when they fly. Sometimes a few people have to be inconvenienced for the greater good.I happen to look alot like a single homed ADSL end user at certain levels, but, I'm multihomed. I'd be very annoyed if my ISP started blocking things just because my traffic pattern didn't look like what they expect from a single homed customer.
Why not? I think it's a very good idea. TCP doesn't work if you only use it in one direction, so blocking this doesn't break anything legitimate, but it does stop a whole lot of abuse. (Obviously I'm talking about the case where the lack of return traffic can be determined with a modicum of reliability.)But, TCP to a port that isn't listening (or several ports that aren't listening) _ARE_ what you are talking about blocking. This is not a good idea.
It should be possible to have a host generate special "return traffic" that makes sure that stuff that would otherwise be blocked is allowed through.
I don't think it's desirable or appropriate to have everyone re-engineerBut then you don't seem to have any problems with letting through denial of service attacks so I'm not sure if there is any use in even discussing this with you. Today, about half of all mail is spam, and it's only getting worse. If we do nothing, tomorrow half of all network traffic could be worms, scans and DOS. We can't go on sitting on our hands.