Snort mailing list archives

RE: Help with monitoring sending packet rate


From: Tu Nguyen <nguyen () ucalgary ca>
Date: Wed, 15 May 2002 14:21:38 -0600 (MDT)



On Wed, 15 May 2002, Spitzer, Nathan wrote:


Monitoring throughput to certain devices is probably better handled through
SNMP if thats possible. If you have manageble switchs, you could use MRTG or
similar to alert you to high-traffic situations on individual
ports.

 MRTG might or might not do in this case. This kind of events
might not cause a noticeable spike on our Internet link.
Also, I just want to monitor the packet rate as seen from the
Internet link not every switches (we have quite a large number of
them). The fact that this kind of event
can come from any port on campus makes it more challenging
to monitor.
  As spp_portscan is already doing something similar, I figure
I could mug about to get it to count the the "number of any packets
generated by a station or a subnet in a number of second.

# This is a small sample from my argus.log
...
...
15 May 02 00:31:17    tcp  136.159.xx.xxx.3569   -> xx.xx.69.126.21    1        0         74          0 TIM
15 May 02 00:31:17    tcp  136.159.xx.xxx.62916  -> xx.xx.69.126.21    1        0         74          0 TIM
15 May 02 00:31:17    tcp   136.159.xx.xxx43700  -> xx.xx.69.126.21    1        0         74          0 TIM
15 May 02 00:31:17    tcp  136.159.xx.xxx.6455   -> xx.xx.69.126.21    1        0         74          0 TIM
15 May 02 00:31:17    tcp   136.159.xx.xxx8693   -> xx.xx.69.126.21    1        0         74          0 TIM
15 May 02 00:31:17    tcp  136.159.xx.xxx.51318  -> xx.xx.69.126.21    1        0         74          0 TIM
15 May 02 00:31:17    tcp   136.159.xx.xxx27017  -> xx.xx.69.126.21    1        0         74          0 TIM
15 May 02 00:31:17    tcp  136.159.xx.xxx.25442  -> xx.xx.69.126.21    1        0         74          0 TIM
...
...

Any advise is greaty appreciated.

Tu Nguyen
nguyen () ucalgary ca



Otherwise, you REALLY need to sniff some of that traffic so you could
develop a rule to monitor it. Good as Snort is, its not really setup do
throughput analysis. Just out of curiosity, what port and protocol are the
packets using and what kind of machines are they attempting to DOS?

-----Original Message-----
From: Tu Nguyen [mailto:nguyen () ucalgary ca]
Sent: Wednesday, May 15, 2002 1:46 PM
To: snort-users () lists sourceforge net
Subject: [Snort-users] Help with monitoring sending packet rate



Hi All:
 I am having a problem with some rogue machines that
spew out packets at a very fast rate. I haven't been able
to capture any of these packets but I believe they are identical,
some sort of Dos. The Src IPs are spoofed and they vary but
their destinations are the same.
 I would like to have snort alert me when this happens and
the only signature I can find to identify the incident is by
the sending packet rate. I have been planning to modify
spp_portscan to alert me when packet rate from certain station
or subnet exceed certain threshold but the code looks daunting.
 Does anyone know how to monitor such an event? Or I need
to reinvent the wheel here.
thank you all.

Tu Nguyen
nguyen () ucalgary ca



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