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Thomas P
Asked: 2022-03-02 07:01:51 +0800 CST

Squid regex syntax description?

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From abuse.ch one can get a plain text file with malware distributing URIs. I want to use this as a blacklist for squid proxy (not yet sure about runtime behavior). It should not be to hard to convert the URI file into a regex file for acl aclname url_regex ... using sed, but I struggle to find the squid regex syntax description to identify all special characters, that I have to escape.

squid

1 Answers

  1. Best Answer

    Squid understands GNUregex (Extended Regular Expressions, AKA: ERE REGEXP).
    It does not fully understand Perl Regular Expressions, AKA: PCRE.
    E.x: \w, \d, \W, \D, lookahead, negative lookahead, shy grouping, atomic groups, etc...)

    Working examples:

    ^(outlook-[1-9]\.cdn|attachments|res\.cdn)\.office\.net$
^c[0-9]+.*(powerpoint|word|excel|visio).*[0-9]{2}\.cdn\.office\.net$
^trello-[a-zA-Z0-9]+\.s3\.amazonaws\.com$

    NON WORKING examples but PCRE valid:
    ^(outlook-\d\.cdn|attachments|res\.cdn)\.office\.net$
^c\d+.*(powerpoint|word|excel|visio).*\d{2}\.cdn\.office\.net$
^trello-\w+\.s3\.amazonaws\.com$
^rr?[1-9]-{2,4}sn-(?!.*-apn[a-z]).*\.googlevideo\.com)$

    More info: https://www.gnu.org/software/gnulib/manual/html_node/Regular-expressions.html https://www.gnu.org/software/grep/manual/html_node/Regular-Expressions.html

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