Hi,

On 2014-7-28, at 17:45, Joe Touch <[email protected]> wrote:
> On 7/28/2014 6:52 AM, Eggert, Lars wrote:
>> Protecting the RST is therefore probably impossible.
> 
> I disagree. There are at least two viable approaches:
> 
> 1) require TCP keepalive and block unprotected RSTs
>       this is TCP-AO's approach

True. But you'd need to send keep-alives pretty frequently to see a benefit (= 
detect that the connection is gone faster than you'd do with just a regular 
timeout.)

> 2) block unprotected RSTs *unless* the connection is active
>       i.e., any correct TCP packet resets a short timer,
>       so that the connection allows RSTs only when the
>       timer expires

I read this a few times but remain confused. Did you maybe mean "allow 
unprotected RTSs unless the connection is active?" (Because as written, it 
seems backwards?)

Lars

> 
> FWIW, that timer can be a few seconds - i.e., the time it would take for a 
> reboot.
> 
> #1 requires idle connections to be active and blocks all unprotected RSTs, 
> but cuts a connection (and cleans up state) whenever a connection goes 
> completely cold
> 
> #2 allows connections to go cold, but makes them susceptible to middlebox 
> RSTs during that time
> 
> I think #1 makes more sense for things like BGP and #2 is more useful in the 
> common case, but an implementation can easily allow #2 as the default and #1 
> to be a configuration option.
> 
> Joe

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