Re: Starting off now it's running

["Al Lewis (allewi)" <allewi () cisco com>]

A good place to start would be in the manual/README files. 

In this particular case check out the doc/README.stream5 file and see the section on “small segments”. Copied below:


small_segments <num1> bytes <num2> [ignore_ports port list]

                            - Configure the maximum small segments queued.  
                              This feature requires that detect_anomalies be enabled. 

                              num1 is the number of consecutive segments that will
                              trigger the detection rule. The default value is 
                              "0" (disabled),with a maximum of "2048”.  

                              num2 is the minimum bytes for a segment to be 
                              considered "small". The default value is "0" (disabled),
                              with a maximum of "2048”.  

                              ignore_ports is optional, defines the list of
                              ports in which will be ignored for this rule.
                              The number of ports can be up to "65535”.

                              Example:
                                small_segments 3 bytes 15 ignore_ports 33 44 55
                              A message is written to console/syslog when this 
                              limit is enforced. The generated alert is 129:12



Thanks!

Albert Lewis
ENGINEER.SOFTWARE ENGINEERING
SOURCEfire, Inc. now part of Cisco
Email: allewi () cisco com 








On 4/15/17, 4:18 PM, "Paul Guijt" <paul.guijt () gmail com> wrote:

> Hi all,
>
> I have Snort now running on my Raspberry in IDS mode (thanks Don Mizutani!),
> great. It spits out in /var/log/snort/alerts reports like 
>
>       [**] [129:12:1] Consecutive TCP small segments exceeding threshold
> [**]
>       [Classification: Potentially Bad Traffic] [Priority: 2]
>       04/15-21:21:36.514707 192.168.178.100:2049 -> 192.168.178.28:698
>       TCP TTL:64 TOS:0x0 ID:18139 IpLen:20 DgmLen:128 DF
>       ***AP*** Seq: 0xD8616620  Ack: 0x6982D5A5  Win: 0x103A  TcpLen: 32
>       TCP Options (3) => NOP NOP TS: 1942222394 4294959044
>
> This is an alert about friendly traffic (a NFS connection). 
>
> Where can I learn how to deal with these alerts? How can I suppress
> false-positives like these? 
>
> I can find a truckload of information online about installation of Snort.
> But where to find information on the usage? Am I overlooking something? 
>
> Any help will gladly be appreciated!
>
> Regards,
> Paul
>
>
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