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From "William A. Rowe, Jr." <wr...@rowe-clan.net>
Subject Re: [users@httpd] Setting the Timeout directive to refrain a DoS attacks
Date Thu, 25 Jun 2009 15:47:24 GMT
André Warnier wrote:
> William A. Rowe, Jr. wrote:
>> André Warnier wrote:
>>> fredk2 wrote:
>>>> Would'nt you think that a (simple) timer for the header could fend off
>>>> some
>>>> of the effect.  Can't we assume that if it takes more than 3 second to
>>>> enter
>>>> the header we do not want that client (i'll have to learn to type
>>>> faster in
>>>> telnet :-).
>>>>
>>> For the headers, I think it might help.
>>> But I'm sure that then the attack would switch to sending the headers
>>> fast, and then a long POST body, veeeeery slowly...
>>>
>>> On another track, it seems that the "Event MPM" model of Apache also is
>>> relatively insensitive to the slowloris thing.
>>
>> ... except, again for POST bodies.  Event MPM does not help, there.
>>
> So basically, Fame and Gratitude (and an Apache teeshirt ?) await
> whoever can design an effective strategy against this.

Timeout handling can be refactored to 'behave as advertised'... there is
a discrepancy with the documentation.

But a pure asynchronous server would break 50% of handler and a good chunk
of the filter modules out there.  First, threading stripped them of the
ability to use 'static' storage; now free threading (resuming on an
arbitrary thread) will strip them of using tls storage.  It's a major 3.0
breaking change when this is introduced; it will be but it's not right
around the corner.




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