A DoS attack is anything which denies service.  This could be as
simple as a backhoe going through your fiber drop :)  Or it could be
as nasty as someone knowing that a single CGI query will eat 30
seconds of CPU on your web server, sending that every couple of
seconds would effectively deny service to others attempting to use
your site.  What you describe is just one type of DoS attack.

--Bill

On 7/6/06, Ryan L. Rodrigue <[EMAIL PROTECTED]> wrote:
Just trying to clarify what a DOS (Denial of Service) Attack is.  A DOS attack 
is a flood of malicious TCP packets, such as SYN or ACK Floods, usually with a 
spoofed (fake) ip address. When the router tries to reply, it times out 
eventually, but many more have come in in the mean time.  It is a means of 
eating up all of the resources within a router rendering it basically useless.
[It is very difficult to stop due to the fact the packets are intended for the 
router, not requiring to be passed.][I think]

I think this is what you are talking about. If not, please feel free to correct 
me. >Ryan


   "Even a stopped clock is right twice a day."


-----Original Message-----
From: Chris Buechler [mailto:[EMAIL PROTECTED]
Sent: Thursday, July 06, 2006 3:47 PM
To: [email protected]
Subject: Re: [pfSense Support] denial of service attack


Jeremy Rempel wrote:
> We were getting thousands of requests per second from various hosts
> for files that didn't exist on the apache webserver.  I will try
> setting up the synproxy and see if that helps.  Can someone point me
> to info on setting up synproxy?

If it's legit HTTP requests, your firewall can't further differentiate
between the "good" and the "bad".  It isn't at all aware of your web
server, other than it knows to let TCP 80 to it.  You could (I believe,
no pfS GUI handy ATM and I don't recall 100% for sure) limit the number
of states per source IP in your firewall rules, if you're getting
thousands from a single host.  if it's just a few requests from many
thousands of hosts, you're out of luck there.  For an attack like this,
you really need either something on the web server itself, or a reverse
proxy between your firewall and web server.



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