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--- config:filter_files [2020/08/23 15:17] – Change links from viewcvs/cvsweb to gitlab. digital man
+++ config:filter_files [2023/12/18 19:51] (current) – [Filter Files] Note about file must end in LF 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. Lines may contain up to 1000 characters.
-===== Comparison Sequences =====
+A tab (ASCII 9) character or a new-line (CR or CRLF) sequence will terminate (signify the end of) each comparison pattern. All characters between the first tab character and the new-line sequence may be considered metadata for the comparison pattern.
+To support the correct auto-addition of filters, it's important that **all comparison patterns end in a new-line sequence** (i.e. a non-empty file must end with an LF character).
+===== 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 61: @@
 |''[[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]])|
@@ Line 62: / Line 68: @@
 |''[[phone.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/phone.can|phone.can]]|''[[badphone.msg]]''|Disallowed phone numbers for new users|
 |''[[subject.can]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/text/subject.can|subject.can]]|''[[badsubject.msg]]''|Disallowed subjects in posted messages|
+**New in Synchronet v3.20:**\\
+Comparison patterns in ''.can'' files may contain metadata as tab-delimited ''key=value'' pairs. The keys supported are:
+^ Key  ^ Description  ^
+|''t'' | Date/time stamp of filter addition (in ISO-8601 format) |
+|''e'' | Expiration date/time (in ISO-8601 format) |
+|''p'' | Protocol used (informational only) |
+|''r'' | Reason for filtering (informational only) |
+|''u'' | User name/identification at time of filtering (informational only) |
+|''h'' | Host name of client (informational only) |
 ===== Other Filter Files =====
@@ Line 69: / Line 85: @@
 ^Filename / Page     ^Default Contents^Description^
 |''[[spamblock.cfg]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/ctrl/spamblock.cfg|spamblock.cfg]]|Hostnames and IP addresses blocked from sending e-mail to the [[server:mail|Mail Server]] (see also ''spamblock_exempt.cfg'')|
-|''[[twitlist.cfg]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/ctrl/twitlist.cfg|twitlist.cfg]]|Disallowed (source or destination) e-mail addresses (enclosed in <angle brackets>) or names (see also ''[[email.can]]'')|
+|''[[twitlist.cfg]]''   |[[https://gitlab.synchro.net/sbbs/sbbs/-/raw/master/ctrl/twitlist.cfg|twitlist.cfg]]|Disallowed (source or destination) e-mail/netmail addresses or names (see also ''[[email.can]]'')|
 ===== Filter Exemption Files =====
@@ Line 83: / Line 99: @@
   * [[:config:|Configuration]]
-{{tag>filter abuse spam}}
+{{tag>configuration security abuse spam cfg can}}

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