Re: Protecting against DoS

[Michael Gale <mgale@utilitran.com>]

Hello,

	You could try using a rate limit -- you could allow a machine to make lets say 10 outbound connections a second and then ...

Depending on your network policy you could drop or log all other outbound request.

Michael.



On Tue, 9 Dec 2003 18:51:46 +0200
Pasi Kärkkäinen <pasik@iki.fi> wrote:

> On Tue, Dec 09, 2003 at 09:40:47AM -0700, Michael Gale wrote:
> > Hello,
> > 
> > 	Can you provide more detail on the type of traffic that caused the DOS -- this may help people in the list with suggestions on how to block it :)
> > 
> 
> Yep. It was tcp-connections from the windows box (infected by the worm) to
> some network-ranges on the internet. source-port was pretty much random, but
> the destination was always 80. So the normal 'allow web browsing' rules
> allowed the worm to DoS the linux-firewall.  
> 
> It just opened the connections all the time, but didn't close them. 
> 
> > Michael.
> > 
> 
> -- Pasi Kärkkäinen
>        
>                                    ^
>                                 .     .
>                                  Linux
>                               /    -    \
>                              Choice.of.the
>                            .Next.Generation.
> 


-- 
Michael Gale
Network Administrator
Utilitran Corporation