网址：http://www.xiaojb.com/archives/it/squid26stable1.shtml
下载：
http://www.squid-cache.org/Versions/v2/2.6/squid-2.6.STABLE1.tar.gz
http://www.squid-cache.org/Versions/v2/2.6/squid-2.6.STABLE1.tar.bz2
2.6和2.5的主要变动
* Major improvements to the way that Squid handles web proxy, accelerated and transparent proxy requests to make it easier to configure transparent and acceleration functionality. The default behaviour is to function as a standard HTTP proxy on each port that Squid is configured to listen on, but in addition in this release the keywords “accelerated” and “transparent” can be specified after each port to indicate to Squid the functionality that is to be enabled on that port. This means that the old config directives relating to httpd_accel_* are now deprecated.
* WCCPv2 support multiple cache engines registering with multiple WCCP routers and switches. WCCPv2 is preferred over WCCPv1 for performance and flexibility reasons if your router or switch is able to support it (all recent versions of IOS do so). Initially WCCPv2 under Linux is limited to registration with only one router due to kernel limitations in more recent versions, although this will be addressed in a future release of Squid.
* TPROXY totally transparent proxy support under Linux, which to allow Squid to appear totally invisible to both client and server systems when transparently caching requests. This works by spoofing the source and destination address to both the client and server.
* Support for Etag and Vary HTTP headers. This further moves Squid towards HTTP/1.1 compliance. The Vary header field is used for improved caching and delivery of customized content to end clients, and the Etag is used similar to an MD5 checksum between client and server to determine if a web page has changed since it was last retrieved.
* Collapsed forwarding, which gives Squid the ability to intelligently merge client requests for objects into one request to the server. Of particular benefit in accelerator setups but also provides some benefits to non accelerator setups.
* Support for epoll under Linux and kqueue under FreeBSD, which gives Squid the ability to handle many many more concurrent requests with lower CPU overhead. This feature is of particular benefit to very busy caches as the poll() and select() routines do not scale anywhere near as well as epoll and kqueue does under high loads.
* SSL assisted hardware encryption making use of OpenSSL functionality within Squid.
* Logging enhancements to allow even greater customization of the way Squid logs requests in the access-log or to syslog if required
* Authentication enhancements including Negotiate/Kerberos support, extra workarounds for NTLM clients and others using Microsoft Integrated Login.
* Additional external_acl parameters to support SSL and even more client side parameters.
* ACL changes in conjunction with SSL changes which have been merged, to allow matching based on SSL certificate parameters.
* Improvements to Cygwin support for users who wish to run Squid in a Microsoft Windows/Cygwin environment as a system service.
* New authentication helpers:
o Digest LDAP helper
o Native Windows basic, NTLM and negotiate helpers
o External acl helpers for session monitoring and native Windows group membership check
* HTCP significantly cleaned up and added support for the CLR operation to purge contents from the cache
* Support for parsing X-Forwarded-For headers allowing access controls to be based on the real client IP even if behind secondary proxies
更多的看这里http://www.squid-cache.org/Versions/v2/2.6/squid-2.6.STABLE1-RELEASENOTES.html
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