+<sect3 renderas="sect4" id="client-specific-tag"><title>client-specific-tag</title>
+<variablelist>
+ <varlistentry>
+ <term>Specifies:</term>
+ <listitem>
+ <para>
+ The name of a tag that will always be set for clients that
+ requested it through the webinterface.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Type of value:</term>
+ <listitem>
+ <para>
+ <replaceable>Tag name followed by a description that will be shown in the webinterface</replaceable>
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Default value:</term>
+ <listitem>
+ <para>None</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Notes:</term>
+ <listitem>
+ <warning>
+ <para>
+ This is an experimental feature. The syntax is likely to change
+ in future versions.
+ </para>
+ </warning>
+ <para>
+ Client-specific tags allow Privoxy admins to create different
+ profiles and let the users chose which one they want without
+ impacting other users.
+ </para>
+ <para>
+ One use case is allowing users to circumvent certain blocks
+ without having to allow them to circumvent all blocks.
+ This is not possible with the
+ <link linkend="enable-remote-toggle">enable-remote-toggle feature</link>
+ because it would bluntly disable all blocks for all users and also affect
+ other actions like filters.
+ It also is set globally which renders it useless in most multi-user setups.
+ </para>
+ <para>
+ After a client-specific tag has been defined with the client-specific-tag
+ directive, action sections can be activated based on the tag by using a
+ <ulink url="actions-file.html#CLIENT-TAG-PATTERN">CLIENT-TAG</ulink> pattern.
+ The CLIENT-TAG pattern is evaluated at the same priority
+ as URL patterns, as a result the last matching pattern wins.
+ Tags that are created based on client or server headers are evaluated
+ later on and can overrule CLIENT-TAG and URL patterns!
+ </para>
+ <para>
+ The tag is set for all requests that come from clients that requested
+ it to be set.
+ Note that "clients" are differentiated by IP address,
+ if the IP address changes the tag has to be requested again.
+ </para>
+ <para>
+ Clients can request tags to be set by using the CGI interface <ulink
+ url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>.
+ The specific tag description is only used on the web page and should
+ be phrased in away that the user understand the effect of the tag.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Examples:</term>
+ <listitem>
+ <para>
+ <screen>
+ # Define a couple of tags, the described effect requires action sections
+ # that are enabled based on CLIENT-TAG patterns.
+ client-specific-tag circumvent-blocks Overrule blocks but do not affect other actions
+ disable-content-filters Disable content-filters but do not affect other actions
+ </screen>
+ </para>
+ </listitem>
+ </varlistentry>
+</variablelist>
+</sect3>
+
+<!-- ~ End section ~ -->
+
+<sect3 renderas="sect4" id="client-tag-lifetime"><title>client-tag-lifetime</title>
+<variablelist>
+ <varlistentry>
+ <term>Specifies:</term>
+ <listitem>
+ <para>
+ How long a temporarily enabled tag remains enabled.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Type of value:</term>
+ <listitem>
+ <para>
+ <replaceable>Time in seconds.</replaceable>
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Default value:</term>
+ <listitem>
+ <para>60</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Notes:</term>
+ <listitem>
+ <warning>
+ <para>
+ This is an experimental feature. The syntax is likely to change
+ in future versions.
+ </para>
+ </warning>
+ <para>
+ In case of some tags users may not want to enable them permanently,
+ but only for a short amount of time, for example to circumvent a block
+ that is the result of an overly-broad URL pattern.
+ </para>
+ <para>
+ The CGI interface <ulink
+ url="http://config.privoxy.org/client-tags">http://config.privoxy.org/client-tags</ulink>
+ therefore provides a "enable this tag temporarily" option.
+ If it is used, the tag will be set until the client-tag-lifetime
+ is over.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Examples:</term>
+ <listitem>
+ <para>
+ <screen>
+ # Increase the time to life for temporarily enabled tags to 3 minutes
+ client-tag-lifetime 180
+ </screen>
+ </para>
+ </listitem>
+ </varlistentry>
+</variablelist>
+</sect3>
+
+<!-- ~ End section ~ -->
+
+<sect3 renderas="sect4" id="trust-x-forwarded-for"><title>trust-x-forwarded-for</title>
+<variablelist>
+ <varlistentry>
+ <term>Specifies:</term>
+ <listitem>
+ <para>
+ Whether or not Privoxy should use IP addresses specified with the X-Forwarded-For header
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Type of value:</term>
+ <listitem>
+ <para>
+ <replaceable>0 or one</replaceable>
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Default value:</term>
+ <listitem>
+ <para>0</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Notes:</term>
+ <listitem>
+ <warning>
+ <para>
+ This is an experimental feature. The syntax is likely to change
+ in future versions.
+ </para>
+ </warning>
+ <para>
+ If clients reach Privoxy through another proxy, for example a load
+ balancer, Privoxy can't tell the client's IP address from the connection.
+ If multiple clients use the same proxy, they will share the same
+ client tag settings which is usually not desired.
+ </para>
+ <para>
+ This option lets Privoxy use the X-Forwarded-For header value as
+ client IP address. If the proxy sets the header, multiple clients
+ using the same proxy do not share the same client tag settings.
+ </para>
+ <para>
+ This option should only be enabled if Privoxy can only be reached
+ through a proxy and if the proxy can be trusted to set the header
+ correctly. It is recommended that ACL are used to make sure only
+ trusted systems can reach Privoxy.
+ </para>
+ <para>
+ If access to Privoxy isn't limited to trusted systems, this option
+ would allow malicious clients to change the client tags for other
+ clients or increase Privoxy's memory requirements by registering
+ lots of client tag settings for clients that don't exist.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Examples:</term>
+ <listitem>
+ <para>
+ <screen>
+ # Allow systems that can reach Privoxy to provide the client
+ # IP address with a X-Forwarded-For header.
+ trust-x-forwarded-for 1
+ </screen>
+ </para>
+ </listitem>
+ </varlistentry>
+</variablelist>
+</sect3>
+
+<!-- ~ End section ~ -->
+
+<!-- ~~~~~ New section ~~~~~ -->
+
+<sect3 renderas="sect4" id="receive-buffer-size"><title>receive-buffer-size</title>
+<variablelist>
+ <varlistentry>
+ <term>Specifies:</term>
+ <listitem>
+ <para>
+ The size of the buffer Privoxy uses to receive data from the server.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Type of value:</term>
+ <listitem>
+ <para>
+ <replaceable>Size in bytes</replaceable>
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Default value:</term>
+ <listitem>
+ <para>5000</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Notes:</term>
+ <listitem>
+ <para>
+ Increasing the receive-buffer-size increases Privoxy's memory usage but
+ can lower the number of context switches and thereby reduce the
+ cpu usage and potentially increase the throughput.
+ </para>
+ <para>
+ This is mostly relevant for fast network connections and
+ large downloads that don't require filtering.
+ </para>
+ <para>
+ Reducing the buffer size reduces the amount of memory Privoxy
+ needs to handle the request but increases the number of systemcalls
+ and may reduce the throughput.
+ </para>
+ <para>
+ A dtrace command like:
+ <quote>sudo dtrace -n 'syscall::read:return /execname == "privoxy"/ { @[execname] = llquantize(arg0, 10, 0, 5, 20); @m = max(arg0)}'</quote>
+ can be used to properly tune the receive-buffer-size.
+ On systems without dtrace, strace or truss may be used as
+ less convenient alternatives.
+ </para>
+ <para>
+ If the buffer is too large it will increase Privoxy's memory
+ footprint without any benefit. As the memory is (currently)
+ cleared before using it, a buffer that is too large can
+ actually reduce the throughput.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Examples:</term>
+ <listitem>
+ <para>
+ <screen>
+ # Increase the receive buffer size
+ receive-buffer-size 32768
+ </screen>
+ </para>
+ </listitem>
+ </varlistentry>
+</variablelist>
+</sect3>