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--- config:filter_files [2020/08/23 15:17] – Change links from viewcvs/cvsweb to gitlab. digital man
+++ config:filter_files [2021/11/14 19:08] – [Trash Can Files] Clarify that ip.can and host.can can be used to filter networked messages digital man
@@ Line 3: / Line 3: @@
 Filter configuration (''[[dir:ctrl]]/*.cfg'') and trash can (''[[dir:text]]/*.can'') files allow the sysop to specify words (or any sequence of characters) that will be used to disallow clients, users, or their content.
-Each line in a filter file may contain a comparison sequence.  Blank lines and lines beginning with a semicolon are ignored.
+Each line in a filter file may contain a comparison pattern.  Blank lines and lines beginning with a semicolon character ('';'') are ignored.
-===== Comparison Sequences =====
+===== Comparison Patterns =====
   * Leading white-space characters are ignored
-  * Sequences of alphabetic letters are treated case-insensitively
+  * Alphabetic character are compared case-insensitively
-  * C-style string-literal backslash (''\'') [[wp>C_syntax#Strings|escape sequences]] are supported (as of v3.17c)
+  * C-style string-literal backslash (''\'') [[wp>C_syntax#Strings|escape sequences]] are supported in patterns (as of v3.17c)
-  * Sequences //beginning// with an exclamation mark (''!'') negate the match logic for that sequence
+  * Patterns //beginning// with an exclamation mark (''!'') negate the match logic for that pattern
-  * Sequences //beginning// with an asterisk (''*'') match only if the characters following the ''*'' are found at the end of the comparison string
+  * Patterns //ending// with a caret (''^'') match only if the preceding (left most) characters are found at the beginning of the comparison string ((The caret is a legacy pattern matching character made obsolete/redundant by the asterisk))
-  * Sequences //ending// with an asterisk (''*'') or caret (''^'') match only if the characters preceding are found at the beginning of the comparison string
+  * Patterns //ending// with a tilde (''~'') match when the preceding string of characters are found //anywhere// within the comparison string
-  * Sequences //ending// with a tilde (''~'') match when the preceding string of characters are found //anywhere// within the comparison string
+  * Patterns //including// an asterisk (''*'') will match when both the left and right string fragments (on either/both sides of the ''*'') match the comparison string (as of v3.19a) ((Additional (more than one) asterisks in a comparison pattern are not treated specially))
-  * All other sequences are "exact match" string comparisons
+  * All other patterns are "exact match" string comparisons
+**Note:**\\
+There's no effective difference between the patterns "word^" and "word*".
 ==== Examples ====
-  * ''sysop'' in the ''name.can'' file would mean users could not use the name "sysop".
+  * ''sysop'' in the ''name.can'' file would mean new users could not use the name "sysop".
-  * ''sysop*'' would mean users could not use names //beginning// with the word "sysop", like "sysop the" or "sysops".
+  * ''sysop*'' would mean new users could not use names //beginning// with the word "sysop", like "sysop the" or "sysops".
-  * ''sysop~'' would mean users could not use names that have the word "sysop" //anywhere// in them, like "imthesysop" or "Joe Sysop".
+  * ''sysop~'' would mean new users could not use names that have the word "sysop" //anywhere// in them, like "imthesysop" or "Joe Sysop".
 === Match strings with the character sequence "viagra" anywhere within ===
@@ Line 55: / Line 58: @@
 |''[[email.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/email.can|email.can]]|''[[bademail.msg]]''|Disallowed (source or destination) e-mail addresses (see also ''[[twitlist.cfg]]'')|
 |''[[file.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/file.can|file.can]]|''[[badfile.msg]]''|Disallowed filenames for upload|
-|''[[host.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/host.can|host.can]]|''[[badhost.msg]]''|Disallowed hostnames for inbound connections (when hostname lookups are enabled)|
+|''[[host.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/host.can|host.can]]|''[[badhost.msg]]''|Disallowed hostnames for inbound connections (when hostname lookups are enabled) and content|
-|''[[ip.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/ip.can|ip.can]]|''[[badip.msg]]''|Disallowed IP addresses for inbound connections|
+|''[[ip.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/ip.can|ip.can]]|''[[badip.msg]]''|Disallowed IP addresses for inbound connections and content (e.g. messages)|
 |''[[ip-silent.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/ip-silent.can|ip-silent.can]]| |Silently-ignored IP addresses for inbound connections|
 |''[[name.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/name.can|name.can]]|''[[badname.msg]]''|Disallowed user login name/alias (see also [[howto:block-hackers]])|

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