Snort mailing list archives

Re: snort inline (non-drop mode) br0


From: Will Metcalf <william.metcalf () gmail com>
Date: Tue, 1 Feb 2011 20:53:46 -0600

You say you are running inline but not in block mode?  Are you still
running with -Q?

Regards,

Will

On Tue, Feb 1, 2011 at 2:42 PM, Lawrence R. Hughes, Sr.
<lhughes () safemedia com> wrote:
Joel,

Sorry If I did not provide the info you need…here it is: snort 2.8.6.1

 We are experiencing a large percentage of dropped packet… dropped packets
start very low, but on the increase all the time exceeding 70%. please see
attached startup and  perf. monitor report

2.       We see a large number of open sessions  without any reduction.  see
attached perf. monitor  and attached config file

3.       Only 7 rule groups are applied

4.       We have disabled many preprocessors and so rules in an attempt to
debug the dropped packet problem??

5.       We do not detect duplicate traffic, snort is running on BR0 which
is made of eth0 and eth1.

6.       Snort is not on a network tap…running inline without blocking.

7.       We are detecting alerts which are valid alerts.

8.       Machine is duel core, 16GB memory @1333Ghz, fSB 1333Ghz, nic on PCI
2.0 5GBs, Raid SAS 15000RPM



The issue is the dropped packets…..i hope the attached files provide you
with enough info to be able to help

 Thanks,

Larry

----- Original Message -----
From: Joel Esler
To: Lawrence R. Hughes, Sr.
Cc: snort-users () lists sourceforge net
Sent: Tuesday, February 01, 2011 1:45 PM
Subject: Re: [Snort-users] snort inline (non-drop mode) br0
Lawrence,
I keep seeing you post to the list asking about open sessions.  But I never
see any responses to anyone's questions that we ask.
Are you having a problem with open sessions, or are you perceiving it to be
a problem?  What's the problem?  Are you dropping packets?  Are you seeing
duplicate traffic?
Is Snort not detecting things?  What's the issue?
Joel

On Tue, Feb 1, 2011 at 12:59 PM, Lawrence R. Hughes, Sr.
<lhughes () safemedia com> wrote:

Hi,

We use snort inline in the non-drop mode and our sensor is listens on br0.
Could it be that we detect the 3whs (session) with stream5, but don't
detect when the session has ended, thus giving us a high rate of open
sessions?

If this is the case, then what interface would be better to use eth0 or
eth1 (currently both eth0 & eth1 are configed to give us br0) ?

Thanks,
Larry


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--
Joel Esler
Skype:eslerjoel
http://blog.snort.org &&; http://blog.clamav.net

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