[Snort-users] tcp syn flood attack

Luis Daniel Lucio Quiroz luis.daniel.lucio at ...11827...
Mon Jun 14 16:48:33 EDT 2010


thanx
well what i'm trying is to use rate_filter with snortsam.  I've ported 
sucessfully snortsam to use with snortsam to plush fw rules

> rate_filter \
>     gen_id 135, sig_id 1, \
>     track by_dst, \
>     count 10, seconds 60, \
>     new_action fwsam: src[IN], 15 minutes , timeout <T>, \
>     apply_to 10.1.1.100

i wonder if this could work



Le lundi 14 juin 2010 15:15:30, Russ Combs a écrit :
> That rule won't exactly catch a syn flood.  Assuming the rule fires the way
> you want without the detection_filter, it will, with the detection_filter,
> fire when more than 10 such *packets* are received in 60 seconds.
> 
> If you truly want a syn flood detection, you need a rate_filter something
> like this:
> 
> rate_filter \
>     gen_id 135, sig_id 1, \
>     track by_dst, \
>     count 10, seconds 60, \
>     new_action drop, timeout <T>, \
>     apply_to 10.1.1.100
> 
> where <T> is the duration you want to drop before allowing the traffic
> through again.
> 
> That will catch an excessive rate of syns.
> 
> Note that this rate filter applies to the destination IP.  You can also
> write a separate rule and then rate filter that rule.
> 
> Russ
> 
> On Mon, Jun 14, 2010 at 3:48 PM, Luis Daniel Lucio Quiroz <
> 
> luis.daniel.lucio at ...11827...> wrote:
> > Ok, after reading ineed to drop a highg  tcp syn flood, to my squid
> > 
> > is this rule  fine or shall do other tunning
> > 
> > 
> > drop tcp any any > 10.1.1.100 3128 ( \
> > 
> >    msg:”Squid sync flood”;
> >    flow:established,to_server; \
> >    detection_filter: track by_src, count 10, seconds 60; \
> >    sid:1000001; rev:1;)
> > 
> > Reegards,
> > 
> > LD
> > 
> > Le lundi 14 juin 2010 11:58:54, Russ Combs a écrit :
> > > That is documented in the Snort manual and in README.filters in the
> > > tarball.
> > > 
> > > On Mon, Jun 14, 2010 at 12:43 PM, Luis Daniel Lucio Quiroz <
> > > 
> > > luis.daniel.lucio at ...11827...> wrote:
> > > > in 2.8 how is this rule?
> > > > 
> > > > Le lundi 14 juin 2010 10:51:44, Russ Combs a écrit :
> > > > > Snort 2.4 is out of date.  The latest Snort includes a rate-based
> > > > > attack detection capability that addresses syn floods.  Have you
> > 
> > tried
> > 
> > > > downloading
> > > > 
> > > > > the tarball from snort.org and building an inline version?
> > > > > 
> > > > > Russ
> > > > > 
> > > > > On Sun, Jun 13, 2010 at 6:42 PM, black_angel black_angel <
> > > > > 
> > > > > black.sad.angel at ...11827...> wrote:
> > > > > > Hello everybody
> > > > > > my snort inline 2.4 can't detect a syn flood attack using hping3
> > > > > > if someone can help me please to write a rule to avoid this
> > > > > > attack tnx
> > 
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Thanx Russ






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