[Oisf-devel] Question about the stream management module (StreamTcp)

Anoop Saldanha anoopsaldanha at gmail.com
Tue Jul 8 12:29:27 UTC 2014

On Tue, Jul 8, 2014 at 1:49 PM, Victor Julien <victor at inliniac.net> wrote:
> On 07/07/2014 05:04 PM, Anoop Saldanha wrote:
>> On Mon, Jul 7, 2014 at 3:30 AM, Asim Jamshed <asim.jamshed at gmail.com> wrote:
>>> Hi,
>>> I have recently started using Suricata and have been browsing
>>> the code. I have had previous practical and slight development
>>> experience with Snort IDS. In specific, I have been trying to
>>> analyze Suricata's stream management module. I haven't been
>>> able to find enough documentation to answer a few questions I
>>> had regarding the reassembly section of the module. The code
>>> itself is somewhat complicated to follow. Therefore I am posting
>>> the questions here. I apologize in advance if these questions
>>> were previously asked as well.
>>> Q1. For a large (active) TCP flow, how many bytes (or segments)
>>> does the module collect before it flushes it to the detect module.
>>> I know that this variable can be adjusted via configuration file but
>>> what is the default value? What is the name of the config variable
>>> that can help me in changing that value?
>> If unspecified in the config file, it's 2560, else it's specify by the
>> toserver-chunk-size option in the config file.
> By default some randomization is added as well, it will list the value
> that is actually used at startup (if you use -v):
> [10054] 8/7/2014 -- 10:18:33 - (stream-tcp.c:570) <Info>
> (StreamTcpInitConfig) -- stream.reassembly "toserver-chunk-size": 2634
> [10054] 8/7/2014 -- 10:18:33 - (stream-tcp.c:572) <Info>
> (StreamTcpInitConfig) -- stream.reassembly "toclient-chunk-size": 2440

Right.  I missed the randomization part.

Anoop Saldanha

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