On Thu, 2009-06-25 at 10:17 -0500, 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.
> 

It is a bit like an arms race - I guess a solution could be to use a
dedicated thread for reading in POST bodies. 
The best way to stop slowloris is to not allow a single user to cripple
your server in this way, by restricting the number of connections a
single IP can have to your servers. That of course, only leads to it
becoming a DDoS rather than a DoS.

Cheers

Tom



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