[Bro] content gaps (Re: Notice.log)

Vern Paxson vern at icir.org
Wed Dec 13 00:13:50 PST 2006

> I'm wondering what
> is actually indicated by content gap

A content gap occurs when Bro's TCP stream reassembler frees up memory
allocated to previous TCP segments and some of those segments were never
delivered (i.e., were never in-sequence).  It generally indicates the
presence of measurement drops (similar to ack_above_hole), though can
also occur when running on traces that have been filtered.

> I would like to
> know what Content Gap means and the rate (> 1/175) or (> 1/1400).

It's not a rate but rather a range of sequence numbers, so in the
second case, it ranges for 1400 bytes starting at sequence #1 to.


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