doc/webserver/user-manual/filter-file.html

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   4 >The Filter File</TITLE
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  70 ><H1
  71 CLASS="SECT1"
  72 ><A
  73 NAME="FILTER-FILE"
  74 >10. The Filter File</A
  75 ></H1
  76 ><P
  77 > Any web page can be dynamically modified with the filter file. This
  78  modification can be removal, or re-writing, of any web page content,
  79  including tags and non-visible content. The default filter file is
  80  oddly enough <TT
  81 CLASS="FILENAME"
  82 >default.filter</TT
  83 >, located in the config
  84  directory. </P
  85 ><P
  86 > This is potentially a very powerful feature, and requires knowledge of both
  87  <SPAN
  88 CLASS="QUOTE"
  89 >"regular expression"</SPAN
  90 > and HTML in order create custom
  91  filters. But, there are a number of useful filters included with
  92  <SPAN
  93 CLASS="APPLICATION"
  94 >Privoxy</SPAN
  95 > for many common situations.</P
  96 ><P
  97 > The included example file is divided into sections. Each section begins
  98  with the <TT
  99 CLASS="LITERAL"
 100 >FILTER</TT
 101 > keyword, followed by the identifier
 102  for that section, e.g. <SPAN
 103 CLASS="QUOTE"
 104 >"FILTER: webbugs"</SPAN
 105 >. Each section performs
 106  a similar type of filtering, such as <SPAN
 107 CLASS="QUOTE"
 108 >"html-annoyances"</SPAN
 109 >.</P
 110 ><P
 111 > This file uses regular expressions to alter or remove any string in the
 112  target page. The expressions can only operate on one line at a time. Some
 113  examples from the included default <TT
 114 CLASS="FILENAME"
 115 >default.filter</TT
 116 >:</P
 117 ><P
 118 > Stop web pages from displaying annoying messages in the status bar by
 119  deleting such references:</P
 120 ><P
 121 > <TT
 122 CLASS="LITERAL"
 123 >  <P
 124 CLASS="LITERALLAYOUT"
 125 >&nbsp;FILTER:&nbsp;html-annoyances<br>
 126 <br>
 127 &nbsp;#&nbsp;New&nbsp;browser&nbsp;windows&nbsp;should&nbsp;be&nbsp;resizeable&nbsp;and&nbsp;have&nbsp;a&nbsp;location&nbsp;and&nbsp;status<br>
 128 &nbsp;#&nbsp;bar.&nbsp;Make&nbsp;it&nbsp;so.<br>
 129 &nbsp;#<br>
 130 &nbsp;s/resizable="?(no|0)"?/resizable=1/ig&nbsp;s/noresize/yesresize/ig<br>
 131 &nbsp;s/location="?(no|0)"?/location=1/ig&nbsp;s/status="?(no|0)"?/status=1/ig<br>
 132 &nbsp;s/scrolling="?(no|0|Auto)"?/scrolling=1/ig<br>
 133 &nbsp;s/menubar="?(no|0)"?/menubar=1/ig&nbsp;<br>
 134 <br>
 135 &nbsp;#&nbsp;The&nbsp;&#60;BLINK&#62;&nbsp;tag&nbsp;was&nbsp;a&nbsp;crime!<br>
 136 &nbsp;#<br>
 137 &nbsp;s*&#60;blink&#62;|&#60;/blink&#62;**ig<br>
 138 <br>
 139 &nbsp;#&nbsp;Is&nbsp;this&nbsp;evil?&nbsp;<br>
 140 &nbsp;#<br>
 141 &nbsp;#s/framespacing="?(no|0)"?//ig<br>
 142 &nbsp;#s/margin(height|width)=[0-9]*//gi<br>
 143 &nbsp;&nbsp;&nbsp;</P
 144 >
 145  </TT
 146 ></P
 147 ><P
 148 > Just for kicks, replace any occurrence of <SPAN
 149 CLASS="QUOTE"
 150 >"Microsoft"</SPAN
 151 > with
 152  <SPAN
 153 CLASS="QUOTE"
 154 >"MicroSuck"</SPAN
 155 >, and have a little fun with topical buzzwords: </P
 156 ><P
 157 > <TT
 158 CLASS="LITERAL"
 159 >  <P
 160 CLASS="LITERALLAYOUT"
 161 >&nbsp;FILTER:&nbsp;fun<br>
 162 <br>
 163 &nbsp;s/microsoft(?!.com)/MicroSuck/ig<br>
 164 <br>
 165 &nbsp;#&nbsp;Buzzword&nbsp;Bingo:<br>
 166 &nbsp;#<br>
 167 &nbsp;s/industry-leading|cutting-edge|award-winning/&#60;font&nbsp;color=red&#62;&#60;b&#62;BINGO!&#60;/b&#62;&#60;/font&#62;/ig<br>
 168 &nbsp;&nbsp;&nbsp;</P
 169 >
 170  </TT
 171 ></P
 172 ><P
 173 > Kill those pesky little web-bugs:</P
 174 ><P
 175 > <TT
 176 CLASS="LITERAL"
 177 >  <P
 178 CLASS="LITERALLAYOUT"
 179 >&nbsp;#&nbsp;webbugs:&nbsp;Squish&nbsp;WebBugs&nbsp;(1x1&nbsp;invisible&nbsp;GIFs&nbsp;used&nbsp;for&nbsp;user&nbsp;tracking)<br>
 180 &nbsp;FILTER:&nbsp;webbugs<br>
 181 <br>
 182 &nbsp;s/&#60;img\s+[^&#62;]*?(width|height)\s*=\s*['"]?1\D[^&#62;]*?(width|height)\s*=\s*['"]?1(\D[^&#62;]*?)?&#62;/&#60;!--&nbsp;Squished&nbsp;WebBug&nbsp;--&#62;/sig<br>
 183 &nbsp;&nbsp;&nbsp;</P
 184 >
 185  </TT
 186 ></P
 187 ><DIV
 188 CLASS="SECT2"
 189 ><H2
 190 CLASS="SECT2"
 191 ><A
 192 NAME="AEN2339"
 193 >10.1. The <I
 194 CLASS="EMPHASIS"
 195 >+filter</I
 196 > Action</A
 197 ></H2
 198 ><P
 199 > Filters are enabled with the <A
 200 HREF="actions-file.html#FILTER"
 201 TARGET="_top"
 202 ><SPAN
 203 CLASS="QUOTE"
 204 >"+filter"</SPAN
 205 ></A
 206 > action from within
 207  one of the actions files. <SPAN
 208 CLASS="QUOTE"
 209 >"+filter"</SPAN
 210 > requires one parameter, which
 211  should match one of the section identifiers in the filter file itself. Example:</P
 212 ><TABLE
 213 BORDER="0"
 214 BGCOLOR="#E0E0E0"
 215 WIDTH="100%"
 216 ><TR
 217 ><TD
 218 ><PRE
 219 CLASS="SCREEN"
 220 >  +filter{html-annoyances}</PRE
 221 ></TD
 222 ></TR
 223 ></TABLE
 224 ><P
 225 > This would activate that particular filter. Similarly, <SPAN
 226 CLASS="QUOTE"
 227 >"+filter"</SPAN
 228 >
 229  can be turned off for selected sites as:
 230  <SPAN
 231 CLASS="QUOTE"
 232 >"-filter{html-annoyances}"</SPAN
 233 >. Remember too, all actions are off by
 234  default, unless they are explicity enabled in one of the actions files.</P
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