Re: snot processes packets twice?

[jorbru30 () comcast net]

Thank you Ru ss for the tip . 



I checked for any bridge but there is none. 



mysnort @home:~/pcaps$ brctl show 
bridge name bridge id  STP enabled interfaces 


I captured pcaps at eth0 and eth1 and each show about 25,000 packets. 



I also added a print statement  prior to " ProcessPacket" in snort.c to verify snort is indeed inspecting duplicate 
packets. My findings is yes, it does inspect about 5 0,000 packets. 



I am still trying to figure out why snort checks packets from both interface and how to fix the issue. 



I appreciate any help . 



Jorda.  


----- Original Message -----


From: "Russ Combs" <rcombs () sourcefire com> 
To: jorbru30 () comcast net 
Cc: snort-users () lists sourceforge net 
Sent: Wednesday, June 27, 2012 10:56:47 AM 
Subject: Re: [Snort-users] snot processes packets twice? 

Not sure why you are seeing double; any chance you bridged eth0 and eth1? 


On Wed, Jun 27, 2012 at 1:18 AM, < jorbru30 () comcast net > wrote: 






Hi, 

  

I am running snort version 2.9.1 as IPS using the following command. 

  

/usr/local/snort/bin/snort --daq afpacket -i eth0:eth1 -Q --daq-dir=/usr/local/lib/daq -l /var/log/snort -c 
/usr/local/snort/etc/snort.conf 


I am sending packets from a traffic generator tool which acts as a sender and receiver. 

      Traffic generator(TGS)<-> eth0 <->eth1 <-> Traffic generator(TGR) 

  

About 25,000 packets are seen at eth0 (packets sent from TGS and responses(mostly ack packets) from TGR).  The same set 
of packets are seen at eth1. 

  

After I stopped snort with ctr-c, snort displays ..."Snort processed 50531 packets". 

  

I was expecting snort to process incoming packets (packets from eth0 to eth1) and outgoing packets (packets from eth1 
to eth0) which is about 25,000 but it processes double # of packets. 

  

Please help me understand why snort process packets twice. 

  

Thank you! 

  

Jorda. 
------------------------------------------------------------------------------ 
Live Security Virtual Conference 
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ 
_______________________________________________ 
Snort-users mailing list 
Snort-users () lists sourceforge net 
Go to this URL to change user options or unsubscribe: 
https://lists.sourceforge.net/lists/listinfo/snort-users 
Snort-users list archive: 
http://www.geocrawler.com/redir-sf.php3?list=snort-users 

Please visit http://blog.snort.org to stay current on all the latest Snort news! 



------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/

_______________________________________________
Snort-users mailing list
Snort-users () lists sourceforge net
Go to this URL to change user options or unsubscribe:
https://lists.sourceforge.net/lists/listinfo/snort-users
Snort-users list archive:
http://www.geocrawler.com/redir-sf.php3?list=snort-users

Please visit http://blog.snort.org to stay current on all the latest Snort news!