An engineer configured regular expression “.”\.(pd][Oo][Cc)|[Xx][LI][Ss]|[Pp][Pp][Tt]) HTTP/1 .[01]" on Cisco ASA firewall. What does this regular expression do?
A.
It captures documents in an HTTP network session.
B.
It captures .doc, .xls, and .pdf files in HTTP v1.0 and v1.1.
C.
It captures .doc, .xls, and .ppt files extensions in HTTP v1.0.
D.
It captures Word, Excel, and PowerPoint files in HTTPv1.0 and v1.1.
The regular expression provided is:.\.(pd][Oo][Cc)|[Xx][LI][Ss]|[Pp][Pp][Tt]) HTTP/1 .[01]
This regular expression is designed to match file extensions for Word (.doc), Excel (.xls), and PowerPoint (.ppt) files in HTTP network sessions.
The regular expression uses character classes and alternatives to match different case variations of these file extensions.
The part.\.(pd][Oo][Cc)|[Xx][LI][Ss]|[Pp][Pp][Tt])matches the file extensions, andHTTP/1 .[01]ensures that the match is in the context of HTTP version 1.0 or 1.1.
References
Cisco ASA Regular Expressions Documentation
Understanding Regular Expressions in Network Security
Filtering and Capturing HTTP Traffic with Regex
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