removes data isps article
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@ -11,8 +11,7 @@ This is the source of the official [Chrome Multi-Device documentation](https://d
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2. Open [http://localhost:8000/_preview.html](http://localhost:8000/_preview.html)
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3. You will see the boilerplate with the index.html file already included
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4. To preview another document, add a url paramater with the filename
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* Something like: [http://localhost:8000/_preview.html?data-compression-for-isps.html](http://localhost:8000/_preview.html?data-compression-for-isps.html)
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* Or: [http://localhost:8888/_preview.html?webview/gettingstarted.html](http://localhost:8888/_preview.html?webview/gettingstarted.html)
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* Something like: [http://localhost:8000/_preview.html?webview/gettingstarted.html](http://localhost:8000/_preview.html?webview/gettingstarted.html)
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* Things mostly work but is not exactly the same as viewing through DCC.
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### Deployment
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@ -1,147 +0,0 @@
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{{+bindTo:partials.standard_multidevice_article}}
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<h1>Chrome Data Compression Proxy for Network Administrators, Carriers, and ISPs</h1>
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<p>
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This document provides technical background for network administrators on
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the Chrome Data Compression Proxy for Android (henceforth referred
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to as DCP). It also describes mechanisms that the DCP provides to allow
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network administrators to restrict access to the proxy for specific
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users and URLs.
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</p>
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<section class="collapsible">
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<h2 id="proxy-connection">Proxy Connection</h2>
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<p>
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Enabling the
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<a href="https://support.google.com/chrome/answer/2392284?co=GENIE.Platform%3DAndroid&hl=en">Data Saver</a>
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feature in Chrome establishes a connection between the browser and Google's
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servers to proxy HTTP requests. Pages loaded in
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Incognito tabs are never proxied or optimized. In the vast majority of cases,
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HTTPS traffic is not affected by Data Saver. On extremely slow page loads, Chrome
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will redirect to a Google-hosted domain which serves a transcoded version of the
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page to save data and load faster. This is only used on very slow page loads, or
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when the page might fail to load at all.
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</p>
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<p>
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When possible, the proxy connection is encrypted using SSL. In certain cases, as described
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below, the proxy connection may use unencrypted HTTP/1.1.
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</p>
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<p>
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Google's proxy servers perform various optimizations on the Web page
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content, with the goal of reducing bandwidth usage and improving performance. The DCP
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transcodes images to the WebP format, reduces image quality, compresses and minifies
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Javascript and CSS resources, and applies gzip and other transport-level
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compression.
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</p>
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<p>
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Requests made by the DCP on behalf of users will carry the header
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<code>Via: 1.1 Chrome-Compression-Proxy</code>. The DCP also acts as an
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HTTP-compliant proxy cache. It respects <code>Cache-Control</code> directives,
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including <code>Cache-Control: no-transform</code> which informs the DCP not to
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transcode a given resource.
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</p>
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</section>
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<section class="collapsible">
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<h2 id="client-ip">Identifying the Client IP Address</h2>
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<p>
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Because requests to destination websites are sent from Google's
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servers, the IP address of the client making the connection will reflect
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the location of Google's servers, not the user. The DCP sends the IP
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address of the client in the <code>X-Forwarded-For</code> header with each
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request, for example: <code>X-Forwarded-For: 74.125.239.111</code>
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</p>
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<p>
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Websites should use the <code>X-Forwarded-For</code> header to determine the IP
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address of the client for the purpose of IP geolocation.
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</p>
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</section>
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<section class="collapsible">
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<h2 id="disabling-encryption">Disabling Encryption</h2>
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<p>
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By default, the connection between the browser and the proxy is over
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an encrypted channel. A network administrator can restrict the use
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of encryption for a specific user by blocking access to a canary URL
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(<code>http://check.googlezip.net/connect</code>) and returning a response
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other than a status code 200 with a response body of <code>OK</code>.
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As described below, Chrome issues an in-the-clear request to this URL
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prior to connecting to the DCP. The canary URL is only used for this
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purpose and does not serve any other content.
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</p>
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<p>
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Because downgrading to HTTP does not allow the DCP to use HTTP/2 and other
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protocol-level enhancements, this will incur a performance penalty for
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the user.
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</p>
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<p>
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It is preferable to send an immediate response for the canary URL, rather
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than inducing a DNS or connection timeout, which will not disable use
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of the DCP.
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</p>
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<h3 id="details">Details</h3>
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<p>
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When Chrome starts with the DCP setting enabled, the DCP is
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enabled by the user, or a network interface change occurs, Chrome
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asynchronously issues an in-the-clear HTTP request to the canary URL,
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<code>http://check.googlezip.net/connect</code>.
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</p>
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<p>
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There are three possible outcomes of the canary URL request:
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</p>
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<ul>
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<li>If the response status code is 200 and the response body is <code>OK</code>,
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Chrome uses an encrypted proxy connection for subsequent HTTP requests.</li>
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<li>If the response status code is anything other than 200 or the response
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body is anything other than <code>OK</code>, Chrome uses an unencrypted proxy
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connection.</li>
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<li>If the canary URL request times out or a DNS error occurs, Chrome
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uses an encrypted proxy connection.</li>
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</ul>
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</section>
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<section class="collapsible">
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<h2 id="proxy-bypass">Proxy Bypass</h2>
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<p>
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The Chrome DCP issues a proxy bypass response for URLs matching a list
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of restricted URLs maintained by Google. A proxy bypass causes Chrome to
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disable the use of SSL for the DCP connection for a short time (randomly
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chosen between 1 and 5 minutes). Carriers or network administrators can
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then block or take appropriate action on the request.
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</p>
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<p>
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Proxy Bypass is used mainly for:
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</p>
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<ul>
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<li>Child sexual abuse material, which includes NCMEC, IWF and other lists
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used globally by Google for restricting access to such illegal material</li>
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<li>URLs subject to court-ordered DMCA and other takedowns on Google services</li>
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<li>Country-specific takedown lists, which are applied only to users with IP
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addresses originating in the associated country</li>
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<li>A small number of other sites known not to work well with the DCP (e.g.,
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known carrier billing portal and intranet sites)</li>
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</ul>
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</section>
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{{/partials.standard_multidevice_article}}
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