Docs: Release Notes update for 4.0

[thirdparty/squid.git] / doc / release-notes / release-4.sgml

<!doctype linuxdoc system>
<article>
<title>Squid 4.0.0 release notes</title>
<author>Squid Developers</author>

<abstract>
This document contains the release notes for version 4 of Squid.
Squid is a WWW Cache application developed by the National Laboratory
for Applied Network Research and members of the Web Caching community.
</abstract>

<toc>

<sect>Notice
<p>The Squid Team are pleased to announce the release of Squid-4.0.0 for testing.

This new release is available for download from <url url="http://www.squid-cache.org/Versions/v4/"> or the
 <url url="http://www.squid-cache.org/Download/http-mirrors.html" name="mirrors">.

<p>While this release is not deemed ready for production use, we believe it is ready for wider testing by the community.

<p>We welcome feedback and bug reports. If you find a bug, please see <url url="http://wiki.squid-cache.org/SquidFaq/BugReporting">
   for how to submit a report with a stack trace.

<sect1>Known issues
<p>Although this release is deemed good enough for use in many setups, please note the existence of 
<url url="http://bugs.squid-cache.org/buglist.cgi?query_format=advanced&amp;product=Squid&amp;bug_status=UNCONFIRMED&amp;bug_status=NEW&amp;bug_status=ASSIGNED&amp;bug_status=REOPENED&amp;version=4" name="open bugs against Squid-4">.

<p>This release addsa dependency on C++11 support in any cmpiler used to build Squid.
  As a result older C++03 -only and most C++0x compilers will no longer build successfully.
  GCC 4.9+, Clang 3.5+ and ICC 12.0+ are known to have working C++11 support and are usable.
  GCC-4.8 will also build for now despite lack of full C++11 support, but some future features may not be available.

<sect1>Changes since earlier releases of Squid-4
<p>
The Squid-4 change history can be <url url="http://www.squid-cache.org/Versions/v4/changesets/" name="viewed here">.


<sect>Major new features since Squid-3.5
<p>Squid 4 represents a new feature release above 3.5.

<p>The most important of these new features are:
<itemize>
	<item>Helper concurrency channels changes
	<item>Configurable helper queue size
	<item>SSL support removal
	<item>MSNT-multi-domain helper removal
	<item>Secure ICAP
	<item>Elliptic Curve Diffie-Hellman (ECDH)
	<item>Improved SMP support
</itemize>

Most user-facing changes are reflected in squid.conf (see below).


<sect1>Configurable helper queue size
<p>The new queue-size=N option to helpers configuration, allows users 
   to configure the maximum number of queued requests to busy helpers.

<sect1>Helper concurrency channels changes
<p>helper-mux.pl we have been distributing for the past few years to
   encourage use of concurrency is no longer compatible with Squid. If
   used it will spawn up to 2^64 helpers and DoS the Squid server.

<p>Helpers utilizing arrays to handle fixed amounts of concurrency
   channels MUST be re-written to use queues and capable of handling a
   64-bit int as index or they will be vulnerable to buffer overrun and
   arbitrary memory accesses.

<p>32-bit helpers need re-writing to handle the concurrency channel ID
   as a 64-bit integer value. If not updated they will cause proxies to
   return unexpected results or timeout once crossing the 32-bit wrap
   boundary. Leading to undefined behaviour in the client HTTP traffic.


<sect1>SSL support removal
<p>Details in <url url="https://tools.ietf.org/html/rfc6176" name="RFC 6176">
   and <url url="https://tools.ietf.org/html/rfc7568" name="RFC 7568">

<p>SSLv2 is not fit for purpose. Squid no longer supports being configured with
   any settings regarding this protocol. That includes settings manually disabling
   its use since it is now forced to disable by default. Also settings enabling
   various client/server workarounds specific to SSLv2 are removed.

<p>SSLv3 is not fit for purpose. Squid still accepts configuration, but use
   is deprecated and will be removed entirely in a future version.
   Squid default behavour is to follow the TLS built in negotiation mechanism
   which prefers the latest TLS version. But also to accept downgrades to SSLv3.
   Use <em>tls-options=NO_SSLv3</em> to disable SSLv3 support completely.

<p>A new option <em>tls-min-version=1.N</em> is added in place of <em>sslversion=</em>
   to configure the minimum version the TLS negotiation will allow to be used
   when an old TLS version is requested by the remote endpoint.


<sect1>MSNT-multi-domain helper removal
<p>The <em>basic_msnt_multi_domain_auth</em> helper has been removed. The
   <em>basic_smb_lm_auth</em> helper performs the same actions without extra
   Perl and Samba dependencies.


<sect1>Secure ICAP
<p>ICAP services can now be used over TLS connections.

<p>To mark an ICAP service as secure, use an <em>icaps://</em> service URI scheme when
   listing your service via an icap_service directive. The industry is using a
   <q>Secure ICAP</q> term, and Squid follows that convention, but <em>icaps</em> seems more
   appropriate for a <u>scheme</u> name.

<p>Squid uses <em>port 11344</em> for Secure ICAP by default, following another popular
   proxy convention. The old 1344 default for plain ICAP ports has not changed.


<sect1>Elliptic Curve Diffie-Hellman (ECDH)
<p>All listening port which supported Diffie-Hellman key exchange are now updated
   to support Elliptic Curve configuration which allows for forward secrecy with
   better performance than traditional ephemeral Diffie-Hellman.

<p>The http(s)_port <em>dhparams=</em> option is replaced with <em>tls-dh=</em> that
   takes an optional curve name as well as filename for curve parameters. The new
   option configured without a curve name uses the traditional ephemeral DH.

<p>A new <em>options=SINGLE_ECDH_USE</em> parameter is added to enable ephemeral
   key exchanges for Elliptic Curve DH.


<sect1>Improved SMP support
<p>Use of C++11 atomic operations instead of GNU atomics allows a wider range of
   operating systems and compilers to build Squid SMP and multi-process features.
   However this does require a C++11 or C++0x compiler with a recent version of
   the C++ standard library.

<p>IpcIo and Mmapped disk I/O modules are now auto-detected properly which
   enables Rock storage on more systems by default than previously.


<sect>Changes to squid.conf since Squid-3.5
<p>
There have been changes to Squid's configuration file since Squid-3.5.

This section gives a thorough account of those changes in three categories:

<itemize>
	<item><ref id="newtags" name="New tags">
	<item><ref id="modifiedtags" name="Changes to existing tags">
	<item><ref id="removedtags" name="Removed tags">
</itemize>
<p>

<sect1>New tags<label id="newtags">
<p>
<descrip>
	<tag>tls_outgoing_options</tag>
	<p>New tag to define TLS security context options for outgoing
	   connections. For example to HTTPS servers.

	<tag>url_rewrite_timeout</tag>
	<p>Squid times active requests to redirector. This option sets
	   the timeout value and the Squid reaction to a timed out
	   request.

</descrip>

<sect1>Changes to existing tags<label id="modifiedtags">
<p>
<descrip>
	<tag>auth_param</tag>
	<p>New parameter <em>queue-size=</em> to set the maximum number
	   of queued requests.

	<tag>cache_peer</tag>
	<p>New option <em>tls-min-version=1.N</em> to set minimum TLS version allowed.
	<p>All <em>ssloptions=</em> values for SSLv2 configuration or disabling
	   have been removed.
	<p>Removed <em>sslversion=</em> option. Use <em>tls-options=</em> instead.
	<p>Manual squid.conf update may be required on upgrade.

	<tag>external_acl_type</tag>
	<p>New parameter <em>queue-size=</em> to set the maximum number
	   of queued requests.

	<tag>http_port</tag>
	<p>New option <em>tls-min-version=1.N</em> to set minimum TLS version allowed.
	<p>All <em>option=</em> values for SSLv2 configuration or disabling
	   have been removed.
	<p>Removed <em>version=</em> option. Use <em>tls-options=</em> instead.
	<p>New <em>options=SINGLE_ECDH_USE</em> parameter to enable ephemeral
	   ECDH key exchange.
	<p>Deprecated <em>dhparams=</em> option. Use <em>tls-dh=</em> instead.
	   The new option allows to optionally specify an elliptic curve for
	   ephemeral ECDH by adding <em>curve-name:</em> in front of the
	   parameter file name.
	<p>Manual squid.conf update may be required on upgrade.

	<tag>https_port</tag>
	<p>New option <em>tls-min-version=1.N</em> to set minimum TLS version allowed.
	<p>All <em>options=</em> values for SSLv2
	   configuration or disabling have been removed.
	<p>Removed <em>version=</em> option. Use <em>tls-options=</em> instead.
	<p>New <em>options=SINGLE_ECDH_USE</em> parameter to enable ephemeral
	   ECDH key exchange.
	<p>Deprecated <em>dhparams=</em> option. Use <em>tls-dh=</em> instead.
	   The new option allows to optionally specify an elliptic curve for
	   ephemeral ECDH by adding <em>curve-name:</em> in front of the
	   parameter file name.
	<p>Manual squid.conf update may be required on upgrade.

	<tag>icap_service</tag>
	<p>New scheme <em>icaps://</em> to enable TLS/SSL connections to Secure ICAP
	   servers on port 11344.
	<p>New <em>tls-cert=</em> option to set TLS client certificate to use.
	<p>New <em>tls-key=</em> option to set TLS private key matching the client
	   certificate used.
	<p>New <em>tls-min-version=1.N</em> option to set minimum TLS version allowed
	   on server connections.
	<p>New <em>tls-options=</em> option to set OpenSSL library parameters.
	<p>New <em>tls-flags=</em> option to set flags modifying Squid TLS operations.
	<p>New <em>tls-cipher=</em> option to set a list of ciphers permitted.
	<p>New <em>tls-cafile=</em> option to set a file with additional CA
	   certificate(s) to verify the server certificate.
	<p>New <em>tls-crlfile=</em> option to set a file with a CRL to verify the
	   server certificate.
	<p>New <em>tls-domain=</em> option to verify the server certificate domain.

	<tag>refresh_pattern</tag>
	<p>Removed <em>ignore-auth</em>. Its commonly desired behaviour is
	   performed by default with correct HTTP/1.1 revalidation.
	<p>Removed <em>ignore-must-revalidate</em>. Other more HTTP compliant
	   directives can be used to prevent objects from caching.

	<tag>sslcrtd_children</tag>
	<p>New parameter <em>queue-size=</em> to set the maximum number
	   of queued requests.

	<tag>sslcrtvalidator_children</tag>
	<p>New parameter <em>queue-size=</em> to set the maximum number
	   of queued requests.

	<tag>url_rewrite_children</tag>
	<p>New parameter <em>queue-size=</em> to set the maximum number
	   of queued requests.

</descrip>

<sect1>Removed tags<label id="removedtags">
<p>
<descrip>
	<tag>cache_peer_domain</tag>
	<p>Superceded by <em>cache_peer_access</em>. Use dstdomain ACL
	   in the access control list to restrict domains requested.

	<tag>refresh_pattern</tag>
	<p>Option <em>ignore-auth</em> removed. Its original intent was
	   to improve caching. HTTP/1.1 permits caching of authenticated
	   messages under conditions which Squid does check for and obey.

	<tag>sslproxy_cafile</tag>
	<p>Replaced by <em>tls_outgoing_options cafile=</em>.

	<tag>sslproxy_capath</tag>
	<p>Replaced by <em>tls_outgoing_options capath=</em>.

	<tag>sslproxy_cipher</tag>
	<p>Replaced by <em>tls_outgoing_options cipher=</em>.

	<tag>sslproxy_client_certificate</tag>
	<p>Replaced by <em>tls_outgoing_options cert=</em>.

	<tag>sslproxy_client_key</tag>
	<p>Replaced by <em>tls_outgoing_options key=</em>.

	<tag>sslproxy_flags</tag>
	<p>Replaced by <em>tls_outgoing_options flags=</em>.

	<tag>sslproxy_options</tag>
	<p>Replaced by <em>tls_outgoing_options options=</em>.
	<p>All values for SSLv2 configuration or disabling have been removed.
	<p>Manual squid.conf update may be required on upgrade.

	<tag>sslproxy_version</tag>
	<p>Replaced by <em>tls_outgoing_options options=</em>.
	<p>All values for SSLv2 configuration or disabling have been removed.
	<p>Manual squid.conf update may be required on upgrade.

</descrip>


<sect>Changes to ./configure options since Squid-3.5
<p>
There have been some changes to Squid's build configuration since Squid-3.5.

This section gives an account of those changes in three categories:

<itemize>
	<item><ref id="newoptions" name="New options">
	<item><ref id="modifiedoptions" name="Changes to existing options">
	<item><ref id="removedoptions" name="Removed options">
</itemize>


<sect1>New options<label id="newoptions">
<p>
<descrip>

</descrip>

<sect1>Changes to existing options<label id="modifiedoptions">
<p>
<descrip>
	<tag>--enable-auth-basic</tag>
	<p>The <em>MSNT-multi-domain</em> helper has been removed.

	<tag>--enable-diskio</tag>
	<p>Auto-detection of SMP related modules has been fixed to
	   actually auto-detect them without configuring the module
	   list manually.

</descrip>
</p>

<sect1>Removed options<label id="removedoptions">
<p>
<descrip>

</descrip>


<sect>Regressions since Squid-2.7

<p>Some squid.conf options which were available in Squid-2.7 are not yet available in Squid-4

<p>If you need something to do then porting one of these from Squid-2 to Squid-3 is most welcome.

<sect1>Missing squid.conf options available in Squid-2.7
<p>
<descrip>
	<tag>broken_vary_encoding</tag>
	<p>Not yet ported from 2.6

	<tag>cache_peer</tag>
	<p><em>monitorinterval=</em> not yet ported from 2.6
	<p><em>monitorsize=</em> not yet ported from 2.6
	<p><em>monitortimeout=</em> not yet ported from 2.6
	<p><em>monitorurl=</em> not yet ported from 2.6

	<tag>cache_vary</tag>
	<p>Not yet ported from 2.6

	<tag>error_map</tag>
	<p>Not yet ported from 2.6

	<tag>external_refresh_check</tag>
	<p>Not yet ported from 2.7

	<tag>location_rewrite_access</tag>
	<p>Not yet ported from 2.6

	<tag>location_rewrite_children</tag>
	<p>Not yet ported from 2.6

	<tag>location_rewrite_concurrency</tag>
	<p>Not yet ported from 2.6

	<tag>location_rewrite_program</tag>
	<p>Not yet ported from 2.6

	<tag>refresh_pattern</tag>
	<p><em>stale-while-revalidate=</em> not yet ported from 2.7
	<p><em>ignore-stale-while-revalidate=</em> not yet ported from 2.7
	<p><em>negative-ttl=</em> not yet ported from 2.7

	<tag>refresh_stale_hit</tag>
	<p>Not yet ported from 2.7

	<tag>update_headers</tag>
	<p>Not yet ported from 2.7

</descrip>

<sect>Copyright
<p>
Copyright (C) 1996-2015 The Squid Software Foundation and contributors
<p>
Squid software is distributed under GPLv2+ license and includes
contributions from numerous individuals and organizations.
Please see the COPYING and CONTRIBUTORS files for details.

</article>