This commits adds documentation for the entropy keyword.
The entropy keyword calculates the Shannon entropy value for content
with the calculated value used to determine whether an alert occurs.
Ticket: 2224
It takes an argument to match only if the buffer is absent,
or it can still match if the buffer is present, but we test
the absence of some content.
For multi buffers, absent matches if there are 0 buffers.
For file keywords, absent matches if there is no file.
Our code handles Uint ranges as exclusive, but for bsize, our
documentation stated that they're inclusive.
Cf. from uint.rs:
DetectUintMode::DetectUintModeRange => {
if val > x.arg1 && val < x.arg2 {
return true;
}
}
Task #6708
This commit updates the bsize documentation
1. Describe what happens when "content" immediately precedes "bsize"
2. Include the operators and
3. Include examples using the operators.
Add startswith modifier to simplify matching patterns at the start
of a buffer.
Instead of:
content:"abc"; depth:3;
This enables:
content:"abc"; startswith;
Especially with longer patterns this makes the intention of the rule
more clear and eases writing the rules.
Internally it's simply a shorthand for 'depth:<pattern len>;'.
Ticket https://redmine.openinfosecfoundation.org/issues/742
* All sections up to 2 levels deep are now shown regardless of whether they are a separate page
* Rename Xbits and Thresholding for more consistent naming
* Minor adjustment in the Payload Keywords section
In some chapters of the rules documentation, many sections used examples of rules, but these were inserted into images. These have been replaced by text and HTML emphasis.
Additionally, some tables embedded into images were also replaced by reST tables.