RFC 2817:Upgrading to TLS Within HTTP/1.1
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Proxies


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... Section 3 and Section 4 describe the operation of a directly connected client and server. Intermediate proxies must establish an end-to-end tunnel ...


... Upgrade across Proxies ...
... specifies the CONNECT method to establish a tunnel across proxies. ...
... hop-by-hop definition of Upgrade was a deliberate choice. It allows for incremental deployment on either side of proxies, and for optimized protocols between cascaded proxies without the knowledge of ...
... deployment on either side of proxies, and for optimized protocols between cascaded proxies without the knowledge of the parties that are not a part of the change. ...


... 8] by Ari Luotonen of Netscape Communications Corporation. It was widely implemented by HTTP proxies, but was never made a part of any IETF Standards Track document. The method ...



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