Re: getting a full copy of pcap for forensic purposes from Snort

[Y M <snort () outlook com>]

We had a sensor that ran both Snort and Daemonlogger on the same box for a while and we did not notice any increased 
packet drops from Snort perspective, but that was a while ago. 
 
The transparent mode on which you are running PF_RING will  largely affect what full packet capture tool you will use.
 
YM
 
From: kslong () mitre org
To: snort () outlook com
Subject: RE: [Snort-users] getting a full copy of pcap for forensic purposes    from Snort
Date: Thu, 20 Mar 2014 15:02:46 +0000









Makes sense.  I am just not sure how I get Snort to see all the packets also if I have daemon logger listening and 
grabbing packets off the interface.  If you
 are using PF_Ring for the interface, like  a lot of us do, There is a real danger that PF_ring will overwrite a packet 
with a new packet once a process reads from the ring.  If Daemonlogger is quicker, which I assume it would be, Snort 
may not get the chance
 to read all the packets off the ring.
 
 
Kerry
 


From: Y M [mailto:snort () outlook com]


Sent: Thursday, March 20, 2014 9:42 AM

To: Long, Kerry S

Cc: Snort-users

Subject: RE: [Snort-users] getting a full copy of pcap for forensic purposes from Snort


 


Hi Kerry,



I would go with something like daemon logger or netsniff-Ng for full packet captures. Reliefs the overhead from Snort 
as it may start dropping packets.



Thanks

YM



Sent from Mobile







From: 
Long, Kerry S

Sent: 
‎3/‎20/‎2014 4:27 PM

To: snort-users () lists sourceforge net

Subject: 
[Snort-users] getting a full copy of pcap for forensic purposes from Snort



I am trying to create a sensor with Snort that has Snort listening on the interface processing rules and such while 
also creating a full copy of pcap seen on the interface for forensic purposes.  I have enough
 storage to hold about a month of pcap in this instance.  I am familiar with the capability of using a log rule to log 
packets but the problem is that the pcap has to go through all the alert rules first it seems before it can be logged.  
The problem is that
 packets can be dropped as the amount of network traffic increases during the day.
 
I have tried using this in my config file to alleviate the problem:
 
# Per Packet latency configuration
config ppm: max-pkt-time 100, \
   fastpath-expensive-packets, \
   pkt-log
 
and this has helped somewhat but I am still not logging some packets (which for a forensic record is bad) and I am 
missing the benefit of several snort rules that take more than 100 usecs.
 
 
Any ideas how I can get Snort to both log all packets to disk and alert on traffic it sees on the interface.
 
Thanks,
 
 
Kerry


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