[Snort-devel] Trivial question

Russ Combs rcombs at ...402...
Thu Sep 12 15:50:21 EDT 2013

Snort reassembles different protocols differently.  The 17K number is close
to the paf_max default of 16K.  PDUs (protocol data units like an HTTP
response) larger than paf_max are truncated into paf_max blocks for
processing by Snort.  The FTP data channel does not get reassembled in that
fashion.  Simplifying things, in inline IPS mode, it will reassemble every
2 data segments.  Otherwise, every 2 or more acknowledged data segments,
upon acknowledgement.  Typically this will be around 2*1460 = 2920 bytes.

So, based on the limited info in your question, the answer is yes, that is

On Wed, Sep 11, 2013 at 3:17 PM, Reinoud Koornstra <sockstat at ...445...>wrote:

> Dear Everyone,
> When i run http traffic through snort, while snort is in inline mode and
> monitoring the sizeo of the packets, I see that every 4 of more full mtu
> packets a packet of 17k bytes is being processed by snort. I am seeing this
> with most kind of traffic, but not with ftp.
> Is that correct or not?
> Thanks,
> Reinoud.
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