Re: snort black list issue

[anton van der leun <anton () vanderleun com>]

Hi Hui,



I studied yesterday further but I could not find if or what I am doing wrong.

In my opinion a blacklist is a blacklist and everything that is described here should be blocked in a IPS.



the statement:

    If DAQ does not support BLACKLIST verdict, it should drop the first packet. After that, packets in that session 
will be blocked by snort session preprocessor, not reputation.
 



this is what is happening, howeverthe session preprocessor is not dropping.

this rises 2 questions:



1. Can I configure BLACKLIST verdict in the daq module, or nee this special hardware ? 

    (which is strange for me as most snort images are running on normal linux commodity hardware/software)



2. where or how can I configure session preprocessor to block flows that are on the blacklist ?







many thanks again,



anton





[root@snort73]# /usr/local/bin/snort --daq-list
Available DAQ modules:
pcap(v3): readback live multi unpriv
ipfw(v3): live inline multi unpriv
dump(v3): readback live inline multi unpriv
afpacket(v5): live inline multi unpriv



-----Oorspronkelijk bericht-----
Afzender: Hui cao <huica () cisco com>
Verstuurd: Dinsdag 2 Augustus 2016 18:24
Aan: anton van der leun <anton () vanderleun com>; Anton van der Leun <anton () triple-t-services nl>; snort-users () 
lists sourceforge net
Cc: Alexander van der Leun <alex () triple-t-services nl>
Onderwerp: Re: AW: [Snort-users] snort black list issue

 
 Reputation preprocessor is called after session preprocessor. You can capture traffic for that session and look at 
what happened with that session. There are lots of other traffic.
 
 If the DAQ you used support BLACKLIST verdict, DAQ will block the whole session, so snort will not received those 
packets.
 If DAQ does not support BLACKLIST verdict, it should drop the first packet. After that, packets in that session will 
be blocked by snort session preprocessor, not reputation.
 
 Best,
 Hui.
 
 
On 08/02/2016 11:26 AM, anton van der leun wrote:
 
 

Hi Hui,

 


 

 

some more testing:
 
 Aug  2 17:33:04 snort73 snort[2834]: ===============================================================================
 Aug  2 17:33:04 snort73 snort[2834]: Reputation Preprocessor Statistics
 Aug  2 17:33:04 snort73 snort[2834]: Total Memory Allocated: 2257540
 Aug  2 17:33:04 snort73 snort[2834]: Number of packets blacklisted: 9
 Aug  2 17:33:04 snort73 snort[2834]: Number of packets whitelisted: 7698
 Aug  2 17:33:04 snort73 snort[2834]: =========================================================================
 
 telenet <ip blacklisted> 80  (succeeds)
 
 Aug  2 17:33:51 snort73 snort[2834]: ===============================================================================
 Aug  2 17:33:51 snort73 snort[2834]: Reputation Preprocessor Statistics
 Aug  2 17:33:51 snort73 snort[2834]: Total Memory Allocated: 2257540
 Aug  2 17:33:51 snort73 snort[2834]: Number of packets blacklisted: 10
 Aug  2 17:33:51 snort73 snort[2834]: Number of packets whitelisted: 7926
 Aug  2 17:33:51 snort73 snort[2834]: ===============================================================================
 
 with browser to same ip address   (succeeds)
 
 Aug  2 17:35:22 snort73 snort[2834]: ===============================================================================
 Aug  2 17:35:22 snort73 snort[2834]: Reputation Preprocessor Statistics
 Aug  2 17:35:22 snort73 snort[2834]: Total Memory Allocated: 2257540
 Aug  2 17:35:22 snort73 snort[2834]: Number of packets blacklisted: 22
 Aug  2 17:35:22 snort73 snort[2834]: Number of packets whitelisted: 8217
 Aug  2 17:35:22 snort73 snort[2834]: ===============================================================================
 
 So apparantly there are some packes dropped, but not all...
 I can remember that when I was investigation this issue last weekend I saw a lot of retransmits.
 I will make a wireshark trace via a monitor port to see what is going on here and will report the outcome to you later.
 
 In my opinion I believed that the reputation processor looks first to every packet and if it was on the blacklist it 
will be dropped without any further processing, but I think I am wrong on this ?
 
 thanks again,
 anton
 

 


 

 


 

 -----Oorspronkelijk bericht-----
 Afzender: Hui cao <huica () cisco com>
 Verstuurd: Dinsdag 2 Augustus 2016 16:42
 Aan: anton van der leun <anton () vanderleun com>; Anton van der Leun <anton () triple-t-services nl>; snort-users () 
lists sourceforge net
 Cc: Alexander van der Leun <alex () triple-t-services nl>
 Onderwerp: Re: AW: [Snort-users] snort black list issue
 
 
 

Hi Anton,

 You have packets that are whitelisted. Have you checked that either IP is not in whitelist?
 
 Do you have this defined in your rule?
 
 drop ( msg: "REPUTATION_EVENT_BLACKLIST"; sid: 1; gid: 136; rev: 1; )
 
 Best,
 Hui.
 
On 08/02/2016 10:21 AM, anton van der leun wrote:
 
 Reputation Preprocessor Statistics
 Total Memory Allocated: 2257540
 Number of packets blacklisted: 12
 Number of packets whitelisted: 333 
 
 
 

------------------------------------------------------------------------------

_______________________________________________
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://sourceforge.net/mailarchive/forum.php?forum_name=snort-users

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