Re: [tcpm] DoS attack from misbehaving receivers

Caitlin Bestler wrote:
...
>>> Having the sender skip segments will indeed detect a non-compliant
>>> receiver that acks segments that were never sent. But sending
>>> non-contiguous TCP segments is itself not compliant.
>> Technically, that's equivalent to losing or reordering
>> segments. As long as you can't tell the difference from the
>> receiver's point of view, why is this not compliant?
>>
>> Joe
> 
> There's a difference between L3 or L2 dropping a segment
> because a queue was full and L4 simply not generating it.

Not to the receiver!

('goes to intent' - the receiver doesn't know intent).

> Granted, there is no method to prove the difference when
> observing from the other end of the network, but that still
> isn't a reason to bless generation of non-compliant TCP streams.

It's not non-compliant to do something that the receiver can't
differentiate from legitimate behavior.

> A TCP connection is supposed to be a peer-to-peer relationship.
> Once you start playing liar's poker to try to trip up the other
> end things are going to get messy very quickly. What if receivers
> started doing things to try to detect sender's who were sending
> out of order?

What would you do? You can't punish them, since you can't know whether
the network is the cause or not.

The better quote might be a version of the (in)famous "don't attribute
to malice that which can be attributed to ignorance"; my version here
would be:

"don't attribute to malice that which can be attributed to entropy"

Joe

-- 
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Joe Touch
Sr. Network Engineer, USAF TSAT Space Segment

Re: [tcpm] DoS attack from misbehaving receivers

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