Update on protection against slowloris

[Tom Evans]

On Thu, 2009-10-01 at 19:48 +0200, Eirik Øverby wrote:
> On 1. okt. 2009, at 10.59, Tom Evans wrote:
> 
> > On Thu, 2009-10-01 at 02:40 +0200, Thomas Rasmussen wrote:
> >> Martin Turgeon wrote:
> >>> Hi list!
> >>>
> >>> We tested mod_antiloris 0.4 and found it quite efficient, but before
> >>> putting it in production, we would like to hear some feedback from
> >>> freebsd users. We are using Apache 2.2.x on Freebsd 6.2 and 7.2. Is
> >>> anyone using it? Do you have any other way to patch against  
> >>> Slowloris
> >>> other than putting a proxy in front or using the HTTP accept filter?
> >>>
> >>> Thanks for your feedback,
> >>>
> >>> Martin
> >>> _______________________________________________
> >>> freebsd-security at freebsd.org mailing list
> >>> http://lists.freebsd.org/mailman/listinfo/freebsd-security
> >>> To unsubscribe, send any mail to
> >>> "freebsd-security-unsubscribe at freebsd.org"
> >> Hello,
> >>
> >> I am using it succesfully although not under any serious load, same
> >> Apache and FreeBSD versions. I found it easy (compared to the
> >> alternatives) and efficient, and no I don't know of any other ways of
> >> blocking the attack, short of using Varnish or similar. However,
> >> accf_http doesn't help at all, since HTTP POST requests bypass the
> >> filter. HTTP POST can be enabled by passing the -httpready switch to
> >> Slowloris.
> >>
> >> Please report back with your findings, I've been wondering how it
> >> would perform under load.
> >>
> >> Best of luck with it,
> >>
> >> Thomas Rasmussen
> >
> > We use Apache 2.2 with the event MPM. This configuration is immune to
> > slowloris, as it was designed (several years before 'slowloris' came
> > along) to solve that exact problem.
> 
> Without SSL, I presume?
> 
> /Eirik
> 

Yes, we run a prefork MPM apache as a reverse proxy in front of that,
serving just SSL and proxying to the other. We're eagerly awaiting the
release of httpd 2.4, which promotes event MPM to non experimental (as
they've solved the problem with SSL).

Cheers

Tom